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Agriculture is a significant sector inCalifornia's economy, producing nearlyUS$50 billion in revenue in 2018^[update]. There are more than 400commodity crops grown acrossCalifornia, including a significant portion of allfruits,vegetables, andnuts in theUnited States.^[1] In 2017^[update], there were 77,100 unique farms and ranches in the state, operating across 25.3 million acres (10,200,000 hectares) of land. The average farm size was 328 acres (133 ha), significantly less than the average farm size in the U.S. of 444 acres (180 ha).^[1]

Because of its scale, and the naturally arid climate, the agricultural sector uses about40 percent of California's water consumption.^[2] The agricultural sector is also connected to other negative environmental and health impacts, including being one of the principal sources ofwater pollution.

The table below shows the top 21 commodities, by dollar value, produced in California in 2017.^[1] From 2016 to 2017, there were increases by more than 2% in total value for the following crops: almonds, dairy, grapes and cattle. The largest increase was seen inalmond sales, which increased by 10.9% from 2016 to 2017, due to both increases in crop volume produced and the average market price for a pound of almonds. Dairy sales increased 8.2% from 2016 to 2017 due to an increase in the average price for milk, despite a slight decrease in total milk production. Grape sales increased by 3.1% from 2016 to 2017 due to an increase in price per ton of grape (from $832 per short ton ($917/t) in 2016 to $847 per short ton ($934/t) in 2017). Cattle sales also increased by 2.7% from 2016 to 2017.^[3][4]

Orloffet al., 2009 findGlyphosate use in this crop isdriving resistance here.^[5]: 230Blythe, California grows nearly 50,000 acres of Alfalfa. 15,000 acres of this alfalfa land are owned by a Saudi Arabia-basedAlmarai, and this feed is exported to Saudi Arabia.^[6]

Almonds contribute a mean of 0.77 pounds${\displaystyle {\text{N}}_2^{}\text{O}-\text{N}}$ emissions per acre per year in Mediterranean agriculture systems.^[11]

TheFuji variety is a recent import fromFujisaki, Aomori, Japan.^[12][13] Introduced in the 1980s,^[13] it quickly became the most produced apple here.^[12]

For a common pest see§ Cucumber Beetle.^[14]

California farms produce 90% of all U.S.-grownavocados, with the great majority being of theHass variety.^[15] In 2021^[16] the state harvest was 135,500 short tons (122,900 t) on 46,700 acres (18,900 ha) for ayield of 2.9 short tons per acre (6.5 t/ha), and at $2,430 per short ton ($2,679/t) that brought $327,369,000. Drought and heat can significantly reduce the harvest in some years.^[17] The Polyphagous Shothole Borer and the associated diseaseit carries have been a great concern here since their discovery on home avocado trees inLA County in 2012.^[18] Immediatelyeradication andquarantine efforts were instituted, and are continuing.^[18] (See§ Polyphagous shot hole borer below.)

For twoinvasive pests which have significantly reduced grower earnings^[19] see§ Avocado Thrips and§ Persea Mite.

Barley stripe rust was first found nearTehachapi in May 1915 onHordeum murinum by Johnson and reported by Humphreyet al., 1924.^[20]: 9 Hungerford 1923 and Hungerford & Owens 1923 found the pathogen on cultivatedbarley inthe central part of the state and also onH. murinum here.^[20]: 9 See also§ Stripe Rust.

TheCalifornia Blueberry Commission represents growers.^[21]UC IPM providesintegrated pest management plans^[22] for blueberry (Vaccinium spp.).

Almost all of the country'sbroccoli is grown here.^[23] In 2021^[update] that was 11,200 planted acres (4,500 ha), all of which was harvested.^[23] The yield was 130.0 short hundredweight per acre (14,570 kg/ha; 13,000 lb/acre) for a harvest of 1,512,000 short hundredweight (68,600 t; 75,600 short tons).^[23] There was only trace wastage.^[23] Selling at a price of $51.50 per short hundredweight ($0.5150/lb; $1.135/kg), the year sold for $631,455,000.^[23]

For an invasive pest of this crop see the painted bug§ Bagrada hilaris.^[24]

The typicalbiomass ofharvest residue inthe coastal regions is 5 dry short tons per hectare (1.8 t/acre).^[25] This is not necessarily a waste product, as it can be useful as fumigant.^[25]

Caneberries (Rubus spp.) grown here include raspberry (see§ Raspberry),blackberry,dewberry,olallieberry, andboysenberry.^[26]

For a common disease of erect and trailing caneberry (excluding raspberry), see§ Leaf Spot of Caneberry.

TheCalifornia Cherry Board^[32] is a statemarketing order representing growers and intermediaries here.^[33] The USDA FAS'sMarket Access Program funds international advertising especially in Canada, South Korea, Japan, China, and Australia.^[33] The state produces the earliest crop in the year^[33] starting in mid-April.^[34] Lasting until early or mid-June every year, this is the second heaviest harvest afterWashington.^[34]

Planting density is usually about 100 trees per acre (250/ha) and the first real crop will be about six years later.^[34]Honey bees are essential topollination for this crop.^[34]Cultivars grown here^[35] areharvested by hand with the stem (pedicel).^[34]

The center of the state produces a large percentage of the crop^[36] andSan Joaquin County, nearLodi is the highest producing county.^[34] Many of these areBing.^[34] As of 2022^[update] newer Bing strains with better heat tolerance have recently been planted here as well as counties further south.^[34]

Birds are commonpests in cherry orchards.^[37][38]

Citrus cultivation in California began with the Spanish missionaries, who planted oranges and lemons at Baja California around 1739 and atAlta California missions by 1769. Early fruit was thick-skinned and sour, not suited for commercial markets. The first sizable grove was established atMission San Gabriel in 1804, with about 400 trees on six acres. This mission-based agriculture ended with secularization which closed the missions and gave away their lands in 1835.Jean-Louis Vignes likely planted the first private orange grove in Los Angeles in 1834.William Wolfskill was the first commercial citrus grower in California, planting his orchard in Los Angeles in 1841. By 1862, his orchards held two-thirds of California's orange trees, marking him as the founder of the state's commercial citrus industry. TheCalifornia gold rush (from 1849) increased demand for oranges, especially for their vitamin C, which helped preventscurvy among miners. This spurred gradual expansion of orchards. In the early 1870s, Wolfskill's reported profits of $1,000 per acre attracted more farmers to citrus growing.^[39][40]

The 1870s saw the introduction of improved fruit varieties. In 1873,navel orange plants from Brazil were distributed by the U.S. Department of Agriculture.Luther C. Tibbets andEliza Tibbets successfully cultivated these in Riverside, leading to widespread planting of the sweet, seedless navel orange, which became the backbone of the California citrus industry. TheValencia orange, introduced in 1876, matured in summer and fall, complementing the winter-ripening navel and providing oranges year-round. TheEureka lemon (from Sicily) andLisbon lemon (from Spain) were introduced in the same period, offering improved varieties and year-round crops.Grapefruit was introduced from Florida in the 1880s. The completion of major railroads (Southern Pacific in 1877, and theSanta Fe in 1885) and the introduction of ventilated boxcars revolutionized distribution, opening national markets and triggering a planting frenzy in southern California. By 1885, the number of citrus trees in California had grown from 90,000 (in 1875) to 2 million, and to 4.5 million by 1901.^[41]

The 1890s brought pest control advances (spraying, fumigation) and frost protection (heaters, later wind machines). The University of California established itsCitrus Experiment Station in 1907, supporting research and innovation. Cooperative marketing emerged with the formation of the California Fruit Growers Exchange in 1905, later known asSunkist Growers Inc., which helped standardize and market California citrus worldwide.^[42][43]

In the early 20th century California dominated the nation's citrus supply, especially from Los Angeles and Orange counties. Since then the geography has shifted. Florida is now dominant in oranges. By the 1980s, California supplied about 75% of the nation's lemons. It was the second largest orange producer in the U.S., ranked third in grapefruit, and was a major source of limes and tangerines. Today about 90% of the state's citrus production is located in five counties, namely Fresno, Kern, Tulare, Ventura and Riverside. Apart from home gardens, citrus is no longer a factor in Orange and Los Angeles counties.^[44]

TheMediterranean climate affords a lower rate ofpost-harvest disease than in some of the world'sgrowing regions, similar to the Mediterranean itself, Australia, and most of South Africa.^[45]: 6 Postharvest problems that do occur tend to be mostly blue and greenPenicillium spp.^[45]: 6 The Asian citrus psyllid was discovered inSouthern California in 2008 anderadication andquarantine are now underway.^[46][47] (See§ Asian citrus psyllid below.)

Gossypium spp. are extensively grown in theImperial Valley.^[48]

§ Pink Bollworm spread to California from its original introduction in Texas.^[49] Despite wideestablishment elsewhere in the southwest theSan Joaquin Valley did not suffer permanent establishment.^[50] SJV was protected by itssterile insect technique (SIT) program although neighbouring areas were continuously infested.^[50] UC IPM provides management information.^[51]

California was an early adopter ofBt cotton, but at a low proportion ofacreage.^[52] The SJV does not use it at all.^[53] HoweverBt resistance has been slow to develop here and inArizona and inTexas.^[54] In the California/Arizona population Tabashniket al., 2022 find Cry1Ac resistance and Cry2Ab resistance are common but the causative mutations do not cause Vip3Aa resistance.^[55]

§ Bemisia tabaci strain B is common in theImperial Valley.^[56] The use ofpyrethroids in the 1980s failed to control it and in deed caused a population increase.^[56]

The southwest water shortage is reducing yield and acreage in the 2020s.^[57]

Interferometric synthetic aperture radar (InSAR) surveys show this crop is a significant cause ofgroundwater-related subsidence.^[58]

§ 1,3-dichloropropene and§ Chloropicrin are effective against the complex of§ Fusarium oxysporum f. sp. vasinfectum and§ Nematode.^[5]

Ortizet al., 2017 provides apolymerase chain reaction (PCR) method which differentiates the California race 4 strain from all others based on the PHO gene.^[59]University of California Integrated Pest Management (UC IPM) provides practices for its control^[60] includingGlenn County.^[61]

SomePythium spp. are seedborne diseases in cotton.^[62][63] UC IPM provide management information.^[62]

SeveralTetranychus spider mite species are common on cotton here  including the Pacific Spider Mite (Tetranychus pacificus), the Two-Spotted Spider Mite (T. urticae)^[64]: 18 andT. cinnabarinus.^[65]

Eradication of the§ Pink Bollworm in this and neighbouring states was greatly aided by the deployment ofBt cotton.^[66] The eradication program began elsewhere and was extended to the California Cotton Belt in 2007.^[67] Dennehyet al., 2011 find bollworm remained 100% susceptible toCry1Ac andCry2Ab2 through 2005 here and in Arizona.^[68]

Pyrethrins are commonly used in this crop.^[69]

Deynzeet al., 2005 performs the firstgene flow analysis in California cotton.^[70] Deynze findspollinators are responsible for almost 100%.^[70][71]

Lacewings^[72] and whiteflies (§ Bemisia tabaci strain B)^[73] are common pests of this crop.

G. barbadense is grown in a small part of the country including the southern part of this state.^[74]

Delia platura is a commonseed predator of this crop.^[75]

Limonius spp. are pests ofgermination andseedling stage.^[76]

§ Lygus hesperus is often confused for other species including somebeneficial insects.^[77]

Spodoptera praefica is a late season pest and rarely an early season pest.^[78]

§ Blapstinus spp. affect seedlings.^[79]

Empoasca fabae is the most common leafhopper in theSan Joaquin Valley.^[80]

Euschistus servus damagesbolls.^[81]

§ Spodoptera exigua is a pest ofseedlings, young plants, squares and early bolls.^[82]

Caliothrips fasciatus is a pest of the mature plant.^[83]

Thelarvae of§ Heliothis virescens are pests of bolls and squares.^[84]

Gryllus spp. are pests of the early stages.^[65]

Bucculatrix thurberiella's harm is limited to the southern deserts only.^[85]

Autographa californica is found mostly in May and early June here.^[86]

§ Aphis gossypii is the most common aphid in this crop.^[87]

§ Agrotis ipsilon is a pest of the young plants.^[88]

From 1997–2000,^[89] the state's acreage varied between 10,500–11,000 acres (4,200–4,500 ha) bringing in $57,969,000–$67,744,000. By 2021^[16] however the harvest was down to 1,038,500 short hundredweight (47,110 t; 51,920 short tons) from 6,700 acres (2,700 ha) for a yield of 155 short hundredweight per acre (17.4 t/ha; 7.8 short ton/acre), and at $23.2 per short hundredweight ($510/t; $464/short ton) that brought only $24,043,000.

This section is an excerpt fromCalifornia dairy industry.[edit]

TheCalifornia dairy industry is a significant part of the agricultural output of the state of California. Milk has the highest farm revenue among California agricultural commodities. California ranks first out of the fifty states indairy production. In 2020 the state had about 1,300 dairy farms and 1.727 million dairy cows.^[90] As of 2018, the state produced nearly 20 percent of all U.S. milk.^[91]

Over 90% of US production is grown here, and most of that in theCoachella Valley.^[92] The distant second isArizona.^[92] The 2020 harvest was 49,300 short tons (44,700 t) from 12,500 acres (5,100 ha), for ayield of 3.94 short tons per acre (8.8 t/ha).^[92] The year's crop sold for $114 million, an average of $2,320 per short ton ($2,557/t).^[92] The harvest extends from the beginning of October to the middle of December.^[93]

The detection of the Red Palm Weevil (Rhynchophorus ferrugineus) in 2010 was very concerning to this valuable industry.^[94][95] See§ Red Palm Weevil.

Calimyrna is a commoncultivar here.^[96][97]

Commodity figs here suffer from manyinsect pests here. See§ Carpenter worm,§ Darkling ground beetle,§ Dried fruit beetle,§ Freeman sap beetle,§ Confused sap beetle,§ Fig beetle,§ Fig mite,§ Fig scale, and§ Navel orangeworm.

For common diseases see§ Fig Smut and§ Alternaria Rot of Fig.

Relative to traditional farming,aquaculture is a small part of California's agricultural economy, generating only $175 million in 2014.^[98] Oysters, abalone, mussels, channel catfish, rainbow trout, and salmon are farmed commercially.^[99]

UCCE's Vegetable Research & Information Center provides comprehensive production advice for this crop.^[111]

Lettuce (Lactuca sativa) is commercially grown in theCentral Valley,Central Coast, anddeserts (theImperial andCoachella valleys).^[112] It is one of the most labor-intensive crops in the state.^[113]

Aphids are a major problem forlettuce on the Central Coast.^[114] See§ Nasonovia ribisnigri for an important aphid, and§ Toxomerus marginatus and§ Platycheirus stegnus for biocontrols.

The Beet Armyworm (BAW,Spodoptera exigua) is apolyphagous insect pest in this crop.^[115] There is wide geographic variation in timing with BAW, theSan Joaquin Valley being vulnerable more in fall than spring, theCentral Coast late summer, and lower desert valleys September and October in established crops and November and December in young plants.^[115] Natural control is significant, from parasitoidsHyposoter exiguae,Chelonus insularis, andLespesia archippivora, andSpodoptera exigua nuclear polyhedrosis virus (SeNPV).^[116][115]Discing as soon as possible after harvest andweed control to denyalternate hosts will help.^[115] Insecticides used include methoxyfenozide,Bacillus thuringiensis ssp.aizawai, SeNPV,chlorantraniliprole,spinosad,indoxacarb,emamectin benzoate,methomyl,ζ-cypermethrin, andpermethrin.^[115] Inorganic,Bacillus thuringiensis andEntrust are used but note that anyspinosad (including Entrust) will also harm the parasitoids.^[115]

For a common pest see§ Cotton Aphid.

Becausenectarines are hairless peaches, for most information see§ Peaches.

Oaks (genusQuercus) are cultivated forornamental purposes and sometimes foracorns.^[117] For a devastating disease see§ Sudden Oak Death.

Okra is not produced in any significant amount here.^[118]Imperial County grows the largest number of acres in the state.^[118]

Oleander (Nerium spp.) suffers from variousXylella fastidiosa diseases here and there is some question as to whether and to what degree it shares inoculum with other crops including food crops.^[119]

Newton Pierce surveyed olive culture in the state and throughout the country for theUnited States Department of Agriculture (USDA) in 1897.^[120]

Olives throughout the state suffer from theintroduced Olive Fruit Fly.^[121]Neofusicoccum mediterraneum,Diplodia mutila, andD. seriata cause significantdisease here.^[122] More specific controls than currently available are needed forN. mediterraneum in highly susceptiblecultivars, namelySevillano andGordal, and early harvest may be needed forD. seriata.^[122] See§ Olive Fruit Fly,§ Neofusicoccum mediterraneum,§ Diplodia mutila, and§ Diplodia seriata.

TheOlive Oil Commission of California was founded in 2014 as an entity of theState of California. The commission was established as a result of a bill introduced byLois Wolk.^[123] The primary goal is to improve the sales of olive oil grown in California.^[124]

The acreage of table olives declined by 55 percent between 2005 and 2025.^[125]

Soil solarization is an alternative tosoil treatment withmethyl bromide.^[126] Stapletonet al., 2005 eliminate almost 100% ofannual weeds in this crop with solarization alone.^[126] It completely fails againstyellow nutsedge however.^[126]

California is the country's largest grower ofpeaches, producing about 70% of the total.^[127]

TheCalifornia Freestone Peach Association (CFPA)^[128] andCalifornia Canning Peach Association/California Cling Peach Board (CCPA)^[128][129] represent the industry.^[130] (Although the CFPA is a separate incorporation, it has always been operated by the CCPA's staff.) The overwhelming majority of the country's peaches are grown here, in 2020^[update] 468,000 short tons (425,000 t) for sales of $308.3 million.^[131] Since 1980 the total value of the harvest has been slightly increasing.^[131] The acreage (hectares) planted in peach has been declining however, down to 73,000 acres (30,000 ha) as of 2020^[update].^[131]

As of 2021^[update]cling deliveries for processing purposes have been on a downward trend for years.^[132] From 430,000 short tons (390,000 t) in 2010, delivered tonnage declined to 225,000 short tons (204,000 t) in 2021.^[132] Clingyield shows no clear trend over the same time, bouncing between 18.1 short tons per acre (41 t/ha) and 15.3 short tons per acre (34 t/ha).^[132]

Prices have been trending mostly upward, from $317 per short ton ($349/t) in 2012 to $518 per short ton ($571/t).^[132]

CCPA expects 2022 deliveries to be between 214,200–232,400 short tons (194,300–210,800 t) from a yield of 15.3–16.6 short tons per acre (34–37 t/ha).^[132]

UCD hosts one of the majorbreeding programs in the country.^[133] Most of theprivate breeding programs for peach in the country are found in California, with a significant amount of thepublic breeding also being performed here.^[133]

Cultivation is heavily pesticide-dependent.^[134] In the 1970s that put growers on the "pesticide treadmill" – increasing control costs,resistance, and resurgence of previously controlled adversaries.^[134] In response the orchards, the UC system, and Sacramento have put together IPM plans which have increased control and decreased applications.^[134] Fire Blight is a major concern as it is throughout the continent.^[135] Fire Blight is so severe that it largely determines what areas may be commercially successful in pear and which may not, restricted to geographies inhospitable to epidemics.^[135] Even so,antibacterials are necessary.^[135] Experts believe that major efficacy loss or aregulatory ban would effectively endBartlett cultivation here, 55% of the country's pears.^[135]

UCR providesintegrated pest management best practices through UCANR.^[136] Pear Psylla is one of the most serious of these pests, both due to its speed of insecticide resistance evolution and because itvectors^[137] the pear decline phytoplasma.^[138] The Asian pearsP. serotina andP. ussuriensis have been widely used asrootstocks but are not being used in new plantings because their severe vulnerability to the decline phytoplasma.^[138] TheCalifornia Pear Sawfly (Pristiphora abbreviata, not to be confused with the Pear SlugCaliroa cerasi) is a minor pest here and usually easily controlled.^[139] UC IPM recommends Entrust and Success (twoSpinosad formulations).^[139]

Integrated pest management (IPM) has a long history of successful use in this crop.^[140]

California produces 10,000 short tons or 9,100 tonnes of Fuyupersimmons a year. Most persimmons produced in California are seedless.^[141] California and Florida account for most commercial persimmon production in the United States. Most persimmon orchards in the US are small scale (70% less than 1 acre or 0.5 hectares and 90% less than 5 acres or 2 hectares).^[142]

Total pistachio acreage increased from 106,000 to 554,000 acres (43,000 to 224,000 ha) between 2002 and 2022 as the hardy trees can thrive with moderately salty water and soil, which is widespread in parts of the Central Valley.^[143]

Ferrisia gilli is aneconomically significant pest of pistachio here.^[144]F. gilli was formerly known as a California population ofF. virgata, only being studied sufficiently to recognize that it is distinguishable fromF. virgata due to its severe impact on pistachio and almond in this state.^[144]Jackrabbits,cottontails, andbrush rabbits mostly damage pistachio trees when other food sources run out in winter or early spring.^[145]UC IPM recommendsfencing,tree guards,baiting,shooting,repellents, andtrapping.^[145]

Alternaria andBotryosphaeria dothidea are significantfungal diseases of pistachios here which often receivestrobilurin,iprodione,azoxystrobin, andtebuconazole treatments.^[146] See§ Alternaria and§ Botryosphaeria dothidea.

96% of the country'sprunes and >70% ofplums are grown here.^[147] Of that, >80% has come from theSacramento Valley since the 1960s.^[147] For an invasive pest in theBay Area, see§ Plum Bud Gall Mite.^[148]

Pomes grown here include§ Apple and§ Pear. For a common disease see§ Fire Blight.

Inpomegranate (Punica granatum), Black Heart (or "Heart Rot") is one of the most common diseases, as it is around the world.^[45]: 192 See§ Black Heart.

Prunus

ForPrunus spp. see§ Stonefruit.

Over 80% of US raspberries (Rubus spp.) are grown here.^[149] The country's consumption has increased eightfold between 2001 and 2021.^[149] This crop is 15% of the state's fresh berry sales.^[149] Acreage (number of hectares) before 2014 is unknown, but in that year 6,800 acres (2,800 ha) produced 1.4 million short hundredweight (64,000 t; 70,000 short tons) selling for $434 million, then the next year 9,700 acres (3,900 ha) produced 2 million short hundredweight (91,000 t; 100,000 short tons) worth $547 million, and in 2016 9,700 acres (3,900 ha) produced 2.1 million short hundredweight (95,000 metric tons; 100,000 short tons) for $358 million, worth more than the peach harvest and four times the pear harvest.^[149] The state has the opportunity to capture much of the market because as of 2021^[update] most of the raspberry (55%), blackberry, and blueberry market in the country is imported, with Mexico supplying 98% of imported raspberry and they have probably reached their limit.^[149] California produces the most fresh market red raspberries, whileWashington is highest for the processed market.^[149] Because the recent expansion has taken acres that had beenpasture, pest and disease pressure is very small – makingorganic an easy option.^[149] The available acreage for that kind of conversion may have reached the limit as of 2021^[update] however.^[149] Pre-transplantsoil fumigation is necessary inconventional, making organic inviable if this kind of new(-to caneberry) acreage is not available.^[149]Driscoll's is themarketer of 90% of raspberries from California and Mexico sold into the US.^[149]

By 2006, California produced thesecond-largest rice crop in the United States,^[150] after Arkansas, with production concentrated in six counties north ofSacramento.^[151]

California's production is dominated by short- and medium-grainjaponica varieties, including cultivars developed for the local climate such asCalrose, which makes up as much as 85% of the state's crop.^[152]

UC ANR (University of California Division of Agriculture and Natural Resources) has a program specifically forsmall grains.^[153] UCANR providespest management information andcultivation practices and organizes farmer education events.^[153] The small grains grown here are primarilywheat,barley,oats, andtriticale,^[153] see§ Barley and§ Wheat. UC-IPM also produces publications specifically for pest management in these crops.^[154]

Although small grains are not a large part of the overall agricultural productivity of the state, they are important enough in particular locations for ANR to haveExtension workers especially forSan Diego County,^[155]Kings County,^[155]San Joaquin County,^[155]Siskiyou County,^[155]Lassen County,^[155]Sutter- andYuba- andColusa- Counties,^[156][155]Davis,^[155]Kern County,^[155]Woodland, Yolo County,^[155]Tulelake, Siskiyou,^[155]Tulare,^[155] andSonoma.^[157]

Golden State Grains is an industry initiative which also cooperates extensively with theUniversity of California breeding programs.^[158] GSG connects future farmers, present farmers, seed suppliers, processors, and consumers.^[158]

See§ Wild beet for a weed of these crops.

Stonefruits are crops of the genusPrunus. Largest harvests by weight are almond, apricot, cherry, peach and plum.^{[citation needed]}

So much of North America's stonefruit is grown here that almost all availablepropagation material is adapted to California specifically.^[159] Few accessions are available which are appropriate anywhere else.^[159] Even so, these are really made for the previous situation in the state, in which lower densities prevailed and dwarfingrootstocks were not used.^[159] With increasingmechanization there is a need for such rootstocks.^[159]

Strawberries (Fragaria ×ananassa) in the United States are almost entirely grown in California – 86% of fresh and 98% of frozen in 2017^[160] – withFlorida a distant second.^[161][162] The 2017 harvest was 1,461.2 thousand short tons (1,325.6 thousand metric tons) worth $3,100,215,000.^[160] Of that 30.0% was fromMonterey, 28.6% fromVentura, 20.0% fromSanta Barbara, 10.0% fromSan Luis Obispo, and 9.2% fromSanta Cruz.^[160] TheWatsonville/Salinas strawberry zone in Santa Cruz/Monterey, and the Oxnard zone in Ventura, contribute heavily to those concentrations.

Production has risen almostmonotonically, from 2005 when 34,300 acres (13,900 ha) were harvested, yielding 600 short hundredweight per acre (67,000 kg/ha; 60,000 lb/acre), for a total yield of 20,580,000 short hundredweight (933,000 t; 1,029,000 short tons). The average price being $54.60 per short hundredweight ($1.204/kg; $0.5460/lb), the 2005 season's harvest sold for $1,122,834,000.^[160]

TheCalifornia Strawberry Commission is the Agriculture Department body which advocates for strawberry growers. The CSC provides information for both growers^[163] and consumers.^[161] Some towns have annual strawberry festivals, seeStrawberry festival § United States. TheDriscoll's company began with strawberries here and still grows and sells here, and they have since expanded to other states, countries, and types of berries.

Cal Poly runs theStrawberry Center^[164] for both research, and producer education.

Labor costs have increased drastically since 2018 especially in this crop, see§ Labor.

Almost 40% of the state isforest, 39.7 million acres (16.1 million hectares; 62,000 square miles; 161,000 square kilometres).^[165] Of that 16.7 million acres (6.8 million hectares; 26,100 square miles; 68,000 square kilometres) was maintained astimberland as of 1996^[update] of which about 77% issoftwood.^[165] Most lumber grown here is used here in the construction industry and some additional lumber is imported fromnearby states andprovinces.^[165]

The FederalRisk Management Agency providescrop insurance for fresh market tomato here, through the regional office in Davis.^[166] 90% of FMT here comes from nine counties,San Joaquin County,Merced,Fresno,San Diego,Kern,Stanislaus,Kings,Tulare, andSacramento.^[167] In 1999 44,000 acres (18,000 ha) were planted, yielding on average 12.5 short tons per acre (28 t/ha), for a gross dollar yield of $5,500 per acre ($14,000/ha).^[167]

Tomatoes contribute a mean of 1.77${\displaystyle {\text{N}}_2^{}\text{O}-\text{N}}$ emissions pounds per acre (1.98 kg/ha) per year in Mediterranean agriculture systems.^[11]

Varieties used here widely incorporateMeloidogyne resistance.^[168]: 35

California walnuts account for nearly all the walnuts grown in the United States. In 2017, walnut production was the seventh most valuable agricultural commodity in California, valued at $1.59 billion in cash receipts.^[169]

Walnuts contribute a mean of 1.34${\displaystyle {\text{N}}_2^{}\text{O}-\text{N}}$ pounds per acre (1.50 kg/ha) emissions per year in Mediterranean agriculture systems.^[11]

Wheat stripe rust is believed to have been present at or before the 1770s due to newspaper reports at the time, and due to the greater prevalence of stripe thanleaf orstem.^[20]: 3 Hungerford (1923) and Hungerford & Owens (1923) found stripe onwheat here and almost all otherwestern states.^[20]: 9

As first speculated by Tollenaar & Houston 1967,^[170] in some yearsinoculum from theSierra Nevadas initiates the state's epidemics.^[20] Wheat sown in the fall (autumn) in the valleys suffers from stripe rust carried from wild grasses in the mountains.^[20] This is not the only source however, as stripe will alsooverwinter inSacramento Valley wheatcover.^[20] See§ Stripe Rust.

This section is an excerpt fromCalifornia wine.[edit]

California wine production has a rich viticulture history since 1680 whenSpanish Jesuit missionaries plantedVitis vinifera vines native to theMediterranean region in their establishedmissions to producewine forreligious services. In the 1770s,Spanish missionaries continued the practice under the direction of theFather Junípero Serra who planted California's firstvineyard atMission San Juan Capistrano.^[171][172]

California wine production grew steadily afterProhibition,^[173] but was known mostly for itssweet,port-style andjug wine products. As the market favoredFrench brands, California'stable wine business grew modestly,^[174] but quickly gained international prominence at theParis Wine Tasting of 1976, when renowned Frenchoenophiles, in ablind tasting, ranked the California wines higher than the premier French labels in theChardonnay (white) andCabernet Sauvignon (red) categories.^[175] The result caused a'shock' in viticulture industry since France was regarded as foremost producer of the world's finest table wines. This event contributed to expanding the recognition and prestige of vintners in theNew World, specifically, the "Golden State".^[176]

The state produces about ninety percent of theAmerican wine supply and is the fourth largest wine producer among the world's independent nations.^[177][178] California has more than 4,200 wineries ranging from home-grown and small boutiques to large corporations with international distribution, and even more vineyards and growers, at close to 6,000.^[177][179]Wine Country, in Northern California, is an internationally recognized premier wine-growing region.^[180]

In 2022, California meat production exceeded 181 million pounds of beef, 49 million pounds of pork, and 3 million pounds of mutton.^[181]Harris Ranch a ranch andfeedlot operation is California's largestbeef producer, producing 150 million pounds (68 kt) ofbeef per year in 2010.^[182]

In 2024, California's 8,864,000 egg-laying chickens produced 201 million eggs, 2.2% of the US total, while leading states Ohio and Iowa each produced over 1 billion eggs.^[183]

Thedomestic fowl industry suffers from avian malaria.^[184][185]Chickens (Gallus gallus/G. domesticus) andducks (Anas platyrhynchos domesticus) are commonly infected, as well as various wild birds.^[184] Testing has been done since the Herman group made the first reports ofP. relictum infection, in Herman 1951, Hermanet al., 1954, and Reeveset al., 1954.^[184] (See§ Avian malaria and§ Plasmodium relictum for the parasite andvectors, and for testing.)

The Central Valley of California is one of the world's most productive agricultural regions.^[186] More than 230 crops are grown there.^[186] On less than one percent of the total farmland in the United States, the Central Valley produces eight percent of the nation's agricultural output by value: US$43.5 billion in 2013.^[187] The top four counties in agricultural sales (2007 data)in the U.S. are in California's Central Valley: Fresno ($3.731 billion), Tulare ($3.335 billion), Kern ($3.204 billion), and Merced ($2.330 billion).^[188][189]

Its agricultural productivity relies on irrigation both from surface water diversions and from groundwater pumping (wells). About one-sixth of the irrigated land in the U.S. is in the Central Valley.^[190]Central Valley groundwater pollution is an ongoing environmental issue in the area.

There are 6,000almond growers who produced more than 1.8 milliontonnes in 2013, about 60 percent of the world's supply.^[191][192]

Parts of the Valley arequarantine as of July 2022^[update] due to an ongoingpest eradication.^[193][194] The Peach Fruit Fly was found inChowchilla and this is a threat not only here, but could spread to the entire state, and to a lesser degree the entire country and other locations around the world.^[193][194] See§ Peach Fruit Fly.

The Salinas Valley, located withinMonterey County, is one of the most productive agricultural regions in California. Monterey County grows over 50% of the national production for leaf lettuce, head lettuce, and celery. It also produces significant percentages of the country's broccoli, spinach, cauliflower, and strawberries.^[195] The area is also a significant producer of organic produce, with 68,868 acres in cultivation and annual sales of $412,347,000.

California has morecertified organic farms than any other state. In 2016, more than a million acres in the state were certified organic.^[196] CA grows 90% or more of the U.S. production of Organic almonds, artichokes, avocados, broccoli, cauliflower, celery, dates, figs, grapes, strawberries, lemons, lettuce, plums, and walnuts.^[197]

There are two primary laws that regulate organic production: at a federal level, theOrganic Foods Production Act of 1990 and at a state level, the California Organic Food and Farming Act of 2016. Both laws lay out standards for production, processing, handling and retailing that must be followed in order to label a product as "organic". The USDA, California Organic Products Advisory Committee, and the California County Agricultural Commissioners monitor and ensure these standards are followed by administering enforcement actions for any violations.^[198]

Any agricultural operation selling more than $5,000 in products per year is required to acquire organic certification, if they seek to sell their products under the organic label. Multiple organizations are accredited to certify operations organic.^[199]

The largest overallwater users in California are the environment, agriculture and urban/ municipal uses.^[2] In an average year, about 40% ofCalifornia's water consumption, or approximately 34.1 million acre-foot (42,100 million cubic metres), isused for agricultural purposes. However, the exact proportion of total water usage for agriculture varies widely between 'wet' and 'dry' years. In wet years, agriculture is responsible for closer to 30% of total water consumption and in dry years closer to 60%.^[2] Water for agriculture is used to irrigate more than 9 million acres (36,000 square kilometres) of cropland annually.^[200]

Water for agriculture comes from two primary sources:surface water andgroundwater. Surface waters include natural bodies of water along with a network of human-builtreservoirs with aqueducts and canals that carry water from the source to the agricultural users.^[200] Groundwater aquifers range in depth and accessibility across the state, and historically have been used to supplement surface water supplies in dry years.^[201]

California is one of the top five states in water use for livestock. Water withdrawals for livestock use in California were 101–250 million US gallons (380,000,000–950,000,000 L)/day in 2010.^[202]

Saudi Arabian companies and individuals have bought land here and inArizona to benefit from subsidized water.^[203] This has produced criticism because thehay grown isexported to Saudi Arabia.^[203] Around 15% of overall alfalfa production goes to exports.^[204]

Agricultural impacts on water quality concentrate around concerns of the following contaminants: nutrients, pesticides, salts, pollutants, sediment, pathogens, and heavy metals.^[205] These contaminants enter water bodies through above-groundsurface runoff of rainwater or excess irrigation water, or percolating through the soil and leaching into groundwater. Water quality concerns affect most regions of the state and tend to be exacerbated during periods of drought.^[206]

At present, all irrigated agricultural operations in the State are required to participate in the Irrigated Lands Regulatory Program.^[207] The regulatory program began after the California Legislature passed Senate Bill 390 (SB390) in 1990, that eliminated a blanket waiver for agricultural operations to discharge wastewater without any specific environmental standards.^[208]

A major source for Southern California's water supply, both agricultural and urban, is theColorado River from which an aqueduct has been built to transport the water from the river toRiverside.^[209] Colorado River irrigation is essential for agriculture to the Salton Sea Basin, which supports key agriculturally productive areas such as the Imperial Valley.^[210] Another aspect of the agricultural water supply in California is the transfer of water that takes place from northern to southern California. In northern California, theShasta Dam contains the flow of theSacramento River, preserving water for California's use, and pumping stations in theCalifornia Delta extract water transferring that water across theSan Joaquin Valley and southward.^[211] A key component to the distribution of the water supply are the irrigation districts and water agencies who are responsible for delegating water as to meet the demand of those within the area as well as clarify and legal arbitration as to water rights.^[212]

The agency tasked with overseeing the state's water supply and any projects associated with the upkeep of the supply is theCalifornia Department of Water Resources (CDWR).^[213] As part of the 2019-2020 California Spending Plan, the CDWR received $2.336 billion with $833 million going towards projects overseen by theCalifornia Natural Resources Agency and $1.503 billion going towards the control board supervised by theCalifornia Environmental Protection Agency.^[214] One of the CDWR's major projects is theState Water Project (SWP) which distributes 34% of the water that flows through its various channels.^[215] The SWP also is one of the largest suppliers ofhydroelectric power in the state.^[215]

The invasivequagga- andzebra-​mussels reached the state in about 2006 and threaten the already limited supply of farm water.^[216] The mussels have continued to spread and present an ever-expanding threat to pipelines.^[217]

In 2014, California agriculture soils contributed to 51% of statewide greenhouse gas emissions.^[11] California's Mediterranean climate supports irrigation events such as nitrification which encourage nitrous oxide production. Mean nitrous oxide emissions (the biggest contributor to ozone depletion of all the major agricultural greenhouse gases) have been reported to be "four times higher in irrigated compared to rain-fed systems".^[11] Another factor which frequently contributes to increased${\displaystyle {\text{N}}_2^{}\text{O}}$ emissions are warm soil temperatures (a common occurrence in California).^[11]

Some California hunter-gatherer tribes, including theOwens Valley Paiute, developed irrigation.^[218] Native Californians were skilled at gathering materials from plants at all times of the year, allowing the consistent gathering of materials from any and alllocal plants. Depending on when various plants—includingsucculents,flowers, and trees—bloomed or became ripe, different aspects of the plant could be accessed or harvested by Native California peoples.^[219]

Black oak acorn harvests were increased bycultural burning, which stimulated acorn growth and increased biodiversity in the area.^[220]Cultural burning was commonly practiced by throughout California to maintain a healthy landscape that produced quality resources, as theKaruk,Yurok,Hupa peoples all regularly burned areas ofbear grass andCalifornia hazelnut and to encourage the growth of stronger stems that could be used forbasketry.^[221][222]

In the late 1700s, Franciscan missionaries establishedSpanish missions in California. Like earlier Spanish missions established inBaja California, these missions were surrounded by agricultural land, growing crops from Europe and the Americas, and raising animals originating from Europe. Indigenous workers from Baja California made up a large part of the initial labor force on California missions.^[223] In the early 1800s, this flow of laborers from Baja California had largely stopped, and the missions relied on converts from local tribes. By 1806, over 20,000Mission Indians were "attached" to the California missions. As missions were expected to become largely self-sufficient, farming was a critically importantMission industry.George Vancouver visitedMission San Buenaventura in 1793 and noted the wide variety of crops grown: apples, pears, plums, figs, oranges, grapes, peaches, pomegranates, plantain, banana, coconut, sugar cane, indigo, various herbs, and prickly pear.^[224] Livestock was raised for meat, wool, leather, and tallow, and for cultivating the land. In 1832, at the height of their prosperity, the missions collectively owned over 150,000 cattle and over 120,000 sheep. They also raised horses, goats, and pigs.^[225]

The Spanish (1784–1810) and Mexican (1819–1846) governments made a large number of land grants to private individuals from 1785 to 1846. Theseranchos included land taken from the missions following government-imposedsecularization in 1833, after which the missions' productivity declined significantly. The ranchos were focused on cattle, andhides and tallow were their main products. There was no market for large quantities of beef (before refrigeration and railroads) until theCalifornia Gold Rush.

Rapid population growth drove an increase in importation of agricultural products, and, within a few years, a massive growth in in-state agriculture. In the first years of the gold rush, the state relied on agricultural imports arriving by ship, from Australia, Chile, and Hawaii. During these years, there was rapid growth in vegetable farming for local markets. This was followed by an expansion of grain farming.^[226] A shift in the economic dominance of grain farming over cattle raising was marked by the passage of the California "No-Fence Law" of 1874. This repealed the Trespass Act of 1850, which had required farmers to protect their planted fields from free-ranging cattle. The repeal of the Trespass Act required that ranchers fence stock in, rather than farmers fencing cattle out. The ranchers were faced with either the high expense of fencing large grazing tracts or selling their cattle at ruinous prices.^[227][228]

Irrigation was almost nonexistent in California in 1850, but by 1899, 12 percent of the state's improved farmland was irrigated.^[229]

Luther Burbank moved toSanta Rosa, California in 1875, and developed numerous commercially successful varieties of plants over the next 50 years.

The 1902Newlands Reclamation Act funded irrigation projects on arid lands in 20 states including California.

In 1905, the California legislature passed the University Farm Bill, which called for the establishment of a farm school for the University of California (at the time,Berkeley was the sole campus of the university).^[230] The commission took a year to select a site for the campus, a tiny town then known as Davisville.^[230]UC Davis opened its doors as the "University Farm" to 40 degree students (all male) from UC Berkeley in January 1909.

In 1919, theCalifornia Department of Food and Agriculture was established. The department covers state food safety, state protection from invasive species, and promoting the state's agricultural industry.

TheDust Bowl of the 1930s drove many people from the American prairie, and a significant number of theseeconomic migrants relocated to California. Poor migrants from Oklahoma and nearby states were sometimes referred to asOkies, generally a pejorative term. In 1933, the state saw a number ofagricultural labor strikes, with the largest actions against cotton growers. Cherry, grape, peach, pear, sugar beet, and tomato workers were also involved.

In 1942, the United States began theBracero program. Lasting until 1964, this agreement established decent living conditions and a minimum wage for Mexican workers in the United States.

In 1965, theWilliamson Act became law, providing property tax relief to owners of California farmland and open-space land in exchange for agreement that the land will not be developed.

The 1960s and 1970s saw majorfarm worker strikes including the 1965Delano grape strike and the 1970Salad Bowl strike. In 1975, theCalifornia Agricultural Labor Relations Act of 1975 was enacted,^[231] establishing the right tocollective bargaining forfarmworkers in California, a first in U.S. history.^[232] Individuals with prominent roles in farm worker organizing in this period includeCesar Chavez,Dolores Huerta,Larry Itliong, andPhilip Vera Cruz.

Through 1995 there were 50,000Mixtecs every year in California agriculture.^[233] They were about 70% of the 10,000 agricultural laborers inSan Diego County, and had been spreading northwards to also work inOxnard,Santa Maria andMadera County, and even intoOregon andWashington.^[233] They were usually not the only indigenous Mexican ethnic groups –Zapotecs andMayans were also usually working the same jobs.^[233]

In the 2000s and 2010s, Californians voted for propositions which established new protections for farm animals.2008 California Proposition 2 and2018 California Proposition 12 both established minimum requirements for farming egg-laying hens, breeding pigs, and calves raised for veal. Few veal and pig factory farm operations exist in California, so these propositions mostly affect farmers who raise California's 15 million egg-laying hens.^[234]

California nut crimes have involved the theft of millions of dollars of nuts (almonds, pistachios, cashews and pecans) in multiple incidents since 2013.^[235][236]

Water theft for agriculture has been an issue in times of drought, with the State assessing fines up to $1.5 million.^[237][238]

Despite its expansive geography, some pests are so severe, sopolyphagous, and/or so wide-ranging as to be economically significant to the entire state.

In 2022, 181 million pounds of pesticide were applied in California, treating 92 million cumulative acres. The most used pesticides include sulfur, mineral oils,glyphosate,1,3-dichloropropene,Lambda-cyhalothrin,Chloropicrin, andAbamectin.^[239]

TheNavel orangeworm (Amyelois transitella) first entered fromArizona in 1942 and quickly began attacking walnut, date palm, and fig – despite itscommon name it is only a minor pest of citrus.^[240] In the decades since it has become a notorious pest of almond, pistachio,^[240][96] and pomegranate and remains problematic for walnut^[96] and fig^[96][97] as well.^[96]

Thelight brown apple moth (Epiphyas postvittana, often abbreviated to LBAM) is a leafroller moth.^[241] Despite itscommon name it is a pest of awide range of crops, not just apples,.^[241][242] The moth was confirmed to be present in California in 2007, and spraying programs in 2007–2008 lead to theLight brown apple moth controversy.^{[241][243]: 233} Taveneret al., 2011 findsnovaluron works well but only when carried byhorticultural mineral oil.^{[244]: 56 [245]} Hosts include strawberry.^[246]

Asian citrus psyllids (Diaphorina citri) are a majorinvasive threat to citrus.^[46][47]

Sellerset al. findsrodents andlagomorphs (jackrabbits,hares, otherrabbits) do not seem to be a pest of walnut orchards here.^[247] On the other hand, jackrabbits,cottontails, andbrush rabbits are a problem for pistachios.^[145] The lagomorph biocontrolmyxoma virus isepidemiologically endemic in native lagomorphs.^[248]

Olives throughout the state suffer from theintroducedOlive Fruit Fly (Bactrocera oleae) here.^[121] First detected outside its traditionalOld World co-occurrence with the host tree inLos Angeles County in November 1998, it has since spread throughout California and intoBaja andSonora.^{[121][249]: 168} OFF is native to theMediterranean basin and appears in some of the earliest written documents of human history, and is now found throughout much of the world.^[250]

Particular strains of OFF are associated with particularvarieties here.^[250] Burrack & Zalom 2008 find females have strongoviposition preferences for particular varieties and their offspring show better life history performance on those preferred varieties.^[250] The introduction here has spurred muchparasitoid research, hoping to control them withbiological controls.^[250] Daaneet al., 2008, Simeet al., 2006, Simeet al., 2007, Yokohamaet al., 2006, and Yokohamaet al., 2008 all were undertaken to serve this state's need for parasitoids.^[250] Yokohamaet al., 2008 achieves 60% control in cage trials using aPsyttalia cf.concolor.^[250] Daaneet al., 2008 findsP. lounsburyi is especially specific to OFF over other possible hosts, and its selectivity makes it an attractive option.^[250] Daaneet al. 2009 discloses an undescribedPteromalus sp. nr.myopitae first found here.^[250] Overall there is much concern about offtarget impacts if these were to be released.^[250]

Aphid are commoncrop pests here.Nasonovia ribisnigri is one of the most common, especially for lettuce.^[114]

Birds are often pests in fruit cultivation here, especially in cherries.^[37][38] Incherry orchards the most common are crows (Corvus brachyrhynchos), crowned sparrows: (Zonotrichia spp.), European starlings (Sturnus vulgaris), house finches (Carpodacus mexicanus), house sparrows(Passer domesticus), scrub-jays (Aphelocoma californica), andYellow-billed magpies (Pica nuttalli), but also in apple, blueberry, and grape, and theAmerican Robin is a problem for some of these.^[38]

TheGlassy-Winged Sharpshooter (GWSS,Homalodisca vitripennis, syn.H. coagulata) is avector of Pierce's Disease and otherXylella fastidiosa diseases here.^{[251][252][253][254]} Probably present since the late 1980s, the GWSS was only confirmed here in 1994.^[253] GWSS was not obviously a threat until August 1999 when it vectored PD to over 300 acres (120 ha) of vineyard inTemecula, Riverside County, forcing its destruction.^[253] GWSS was first detected inSolano in November 2021, and although as of July 2022^[update] absent from adjacentNapa is considered a high risk forintroduction.^[255] The staff of theNapa County Agriculture Commissioner does inspections of all material entering the county to prevent that from happening.^[255] GWSS is such a problem inFresno that there are permanentquarantine,monitoring, anderadication activities there.^[256]

In 1997 theBlue-Green Sharpshooter (BGSS,Graphocephala atropunctata, the primary PDvector) arrived here and the two have combined badly ever since.^[257] Besides vectoring PD they are also themselves a sucking pest and Hewittet al., 1949 found they will often additionally go through reproduction on the vines.^[258]

TheEuropean Grapevine Moth (Lobesia botrana, EGVM) was present from at least 2009 through 2014.^[259] A 10 acres (4.0 ha)block inNapa suffered a 100%crop loss in 2009 due to a burrowingworm.^[259] This was confirmed to be the EGVM by Gilliganet al., on September 30, 2009 (published in 2011).^[259] (It is native tosouthern Italy and may have arrived elsewhere in the state, possibly being detected as early as 2007 by Mastroet al., and published in 2010).^[259] BothUSDA andCDFA imposequarantines if two moths are found within 3 miles (4.8 km) of each other within onelifecycle span.^[259] At first the quarantine zone was 5 miles (8.0 km) around the detection sites.^[259] In 2010, 40,000traps revealed an expanded presence – inFresno,Mendocino,Merced,Monterey, Napa,San Joaquin,Santa Clara,Santa Cruz,Solano, andSonoma.^[259] The first detection in Sonoma was aroundKenwood on March 29, 2010, then a total of 59 across the County that year.^[259] In 2011 only nine were detected on two sites in Sonoma, and despite the quarantine the pest spread toNevada County in 2011.^[259] The quarantine was lifted in Fresno, Mendocino, Merced, and San Joaquin in February 2012, only one insect was found in Sonoma for the year, the quarantine was lifted in Nevada, Santa Clara, and Santa Cruz counties in December, and was greatly shrunk in Solano and Sonoma in the same month.^[259] No detections occurred in Sonoma in 2013.^[259] The quarantine was lifted in Solano in 2014 but one EGVM was found in Sonoma for the year and so the quarantine remained in Napa and Sonoma.^[259] The last detection being in June 2014 in Sonoma, all USDA and state quarantine and trapping activities ended with the declaration in August 2016 of a successfuleradication.^[259]

Carpenter Worm (Prionoxystus robiniae),^[260]Darkling ground beetle (Blapstinus fuliginosus),^[260]Dried fruit beetle (Carpophilus hemipterus),^[260]Freeman sap beetle (Carpophilus freemani),^[260]Confused sap beetle (Carpophilus mutilatus),^[260]Fig beetle (Cotinis texana syn.C. mutabilis),^[261][260]Fig mite (Aceria fici),^[260]Fig scale (Lepiosaphes conchiformis),^[260] and Navel orangeworm^{[96][97][260]} are among the most important pests of fig here.

Japanese Beetle (Popillia japonica) has been repeatedly found here and repeatedlyeradicated.^[262] Monitoring and eradication continue especially because of thewide host range of the grubs but also due to the grubs' and adults' destructiveness.^[262]

ThePlum Bud Gall Mite (Acalitus phloeocoptes (Nalepa)) was first confirmed here inSanta Clara County in February 2019,^[263] but may have been found in northernMarin in early 2014.^[148] Certainly since 2019 it has become widespread in theBay Area, as of 2021^[update] reachingContra Costa,Alameda,San Mateo,Santa Cruz,Sonoma, and north intoWestern Oregon.^[148] So far PBGM is known to be a problem on plum andpluot and not on other stonefruits, especially not almond.^[148]

TheSilverleaf Whitefly (SLW,Bemisia tabaci strain B) was first noticed here in the fall of 1991.^[264] First appearing in the valleys ofthe state's deserts, it has caused about $500 million in agricultural losses here through 2019.^[264] Further economic effects include $774 million in lost sales, $112.5 million in lost personal income, and the loss of 12,540 jobs.^[264] SLW is intractable in the southern deserts, especially inImperial,Palo Verde,Coachella, and the southern part ofSan Joaquin vallies.^[264] In the SJV this is worst on§ Cotton.^[264] Himleret al., 2011 find theRickettsia sp. nr.bellii symbiont rapidly invaded the population of California,Arizona andNew Mexico.^[265]

Aleyrodes spiraeoides is a native whitefly.^[266] Hosts include strawberry.^[266]

Trialeurodes vaporariorum has recentlyinvaded the Central Coast and Southern areas.^[266] Hosts include strawberry.^[266]

Trialeurodes packardi is a pest of strawberry whiteflies but less commonly thanA. spiraeoides.^[266]

APainted Bug,Bagrada hilaris was first detected here in 2008 inSan Diego,Orange,Los Angeles, 2009 inVentura,Riverside, andImperial counties; 2010 inKern,San Bernardino; no new discoveries here in 2011; 2012 inSanta Barbara &San Luis Obispo; 2013 inMonterey,Santa Cruz,San Benito,Fresno,Tulare,San Francisco; 2014 inInyo,Kings,Merced,Stanislaus,Santa Clara,Alameda,San Mateo, andYolo.^[24] From here it has become aninvasive pest ofBrassicas throughout the southwest US, neighboringCoahuila, and theBig Island of Hawaii.^[24] The most valuable crop threatened is§ Broccoli.^[24] Much of the research on this pest in this part of the world has been performed by the Palumbo group at theUniversity of Arizona.^[24]

Lygus bugs are common pests here including theWestern Tarnished Plant Bug (WTPB,Lygus hesperus).^[267] A vacuum collector is often used for WTPB in strawberry, called the BugVac.^[268]

TheSpotted Wing Drosophila (Drosophila suzukii) is a majorinsect pest of soft body fruits here,^[269][270] especially grape,^[271] strawberry,^[272][273] tomato, cherry,^[274][270] raspberry and othercaneberries,^[275] peach and nectarine,^[270] fig,^[270] and blueberry.^[276]Ganaspis brasiliensis is aparasitoid which has been successful as abiocontrol here.^[273]

OtherDrosophila species includeD. melanogaster andD. simulans whichvector sour rot and bunch rot pathogens between grape bunches.^[271] Hosts include grape^[271] and strawberry.^[277]

Turelliet al., 1991 uses agenetically modifiedWolbachia to suppressD. simulans to suppress its vectored diseases here.^[278] (This has become a widely known example ofWolbachia use, and has informedEuropean decision making onvector control.)^[278]

TheSalt Marsh Caterpillar (Estigmene acrea) is very common here, but usually causes no damage because they are anative pest with manynatural enemies acting asbiocontrols.^[279][280] SMC can be significant in strawberry.^[279][280]

ThePeach Fruit Fly (Bactrocerazonata Saunders) has been repeatedly introduced and quickly eradicated here, in 1984^[281] and in 2006.^{[282][193][194]} Then on September 29 and/or 30, 2020, three PFF were found in Chowchilla, Madera County.^[193][194] This presents a tremendous hazard not only to the area but to the state, and indeed the entire country.^[193][194] Because the pest may spread from here to other countries,trading partners including the European Union and New Zealand are also concerned.^[193][194] They are considering restricting importation of fruits and vegetables from the state.^[194] As a result, the Secretary of CDFA,Karen Ross has declared abiosecurity emergency anderadication efforts usingmethyl eugenol lures are underway.^[193][194] Especially an immediate concern are California's $2.10b citrus-, $875m stonefruit-, and $1.19b tomato industries.^[193][194]

TheGreen Fruit Beetle (Figeater Beetle,Cotinis mutabilis) is occasionally a pest of ripened fruit, including apricot, caneberry, fig, grape, peach, and plum.^[283] Thelarvae/grubs are harmless however.^[283]

ForBeet Armyworms (BAW,Spodoptera exigua) in strawberry^[284] and lettuce^[115]S. exigua populations here have long standingcarbamate resistance.^[285]

First identified here in 1992 inLa Mesa, San Diego County by Haagsmaet al.,^[286] theFormosan Termite (Coptotermes formosanus) has been here since at least 10 years prior.^[287] As with every other infestation anywhere in the world, it has never been eradicated, and is still present at the original La Mesa site.^[287] In the time since there have been new infestations – mostly suspected to be independent introductions – inCanyon Lake, Riverside County in 2020,Rancho Santa Fe, San Diego County in 2021,Highland Park, Los Angeles County in 2021.^[288][289] The Formosan Termite is a pest ofsugarcane, and citrus, but it is most often astructural pest.^[290]

Cucumber Beetles (Diabrotica balteata,Acalymma vittatum,D. undecimpunctata) are common pests here.^[14] UC IPM provides recommended practices for apricot,^[14]

Phylloxera of Grape (Daktulosphaira vitifoliae) is a perennial aphid problem here.^{[291]: 24–25} The industry suffered a wipeout in the 1980s due to overreliance on one, non-resistantrootstock.^{[291]: 24–25} Islamet al., 2013 explains some of thegenetic diversity of the population here bysexual reproduction, but their sampling leaves open other possibilities for the remainder.^[292] They also find two majorsubpopulations differentiated byrootstock association:AxR1 associated and those associated with all others.^[292]

The detection of theRed Palm Weevil (Rhynchophorus ferrugineus) in 2010 was very concerning to this valuable industry.^[94][95] It most likely arrived with in live palms which are commonly sold internationally.^[95] The adults flew up to 900 metres (2,953 ft; 984 yd) in a day, and over 3 to 5 days that allowed dispersal up to 7 kilometres (4.3 mi).^[95] A tremendous effort was made to trap anderadicate,^[94] UCR'sCenter for Invasive Species Research recommended mostly insecticides, and quick destruction of any palms found to be infested. Pheromoneattractant traps were very effective.^[95] TheCalifornia Fan Palm (Washingtonia filifera) and theEuropean Fan Palm (Chamaerops humilis) seemed to be resistant.^[95] The last sighting was on January 18, 2012.^[94] Three years later on January 20, 2015, USDA'sAPHIS declared the eradication successful.^[94] Its relative the South American palm weevil (R. palmarum) has killed increasing numbers of Canary Island date palms (Phoenix canariensis) and is expected to become a significant pest of dates in the future.^[94]

SeveralCulex mosquitoes are common here includingC. quinquefasciatus,C. stigmatosoma, andC. tarsalis.^[184] Insecticides are often used intheir control^[293] and as a result some species have undergoneresistance evolution.^[293] Moucheset al., 1986 finds one population achieved this viagene amplification of anesterase.^[293][294]

The southern part of the state suffers from theWalnut Aphid (Spotted Alfalfa Aphid,Therioaphis trifolii).^[295] Stern & Reynolds 1958 finds that from the beginning of the 1950s to the end of the decade severeparathion resistance had rapidly developed there.^[295]

The commonHouse Fly (Musca domestica) is economically significant in poultry production worldwide, including in California.^[295] From 1964 to 1969 Georghiou & Hawley 1972 finds rapid evolution oforganophosphate resistance in a poultry facility inMoorpark.^[295] The most commonpermethrinkdr allele here iskdr-his, althoughkdr andsuper-kdr are also present.^[296] (This profile is also found inNew Mexican,Floridian,North Carolinian,New York, andMontanan populations.)^[296]

TheMexfly (Mexican fruit fly,Anastrepha ludens) has repeatedly invadedthe southern part of the state.^[297]: 16 Sterile insect technique (SIT) has been used to great success toeradicate them every time, both here and in Texas.^[297]: 16

TheMedfly (Mediterranean fruit fly,Ceratitis capitata) has also been controlled with SIT both here and inFlorida, although before 1980 both states usedmalathion baits.^[297]: 18 Eradication by SIT was accomplished with the help of theNuclear Techniques in Food and Agriculture program, a joint effort of theUnited Nations Food and Agriculture Organization and theInternational Atomic Energy Agency (FAO-IAEA).^[298]: 30 Studies of the Medfly invasion here show that there have been many almost-invasions atthe state's airports and other ports, most of which have failed toestablish^[299] including a small infestation in 1975 inLos Angeles which was eradicated using SIT.^[249]: 174 This has informedquarantine andinvasion biology efforts and studies on the Medfly around the world.^[299]

Tetranychus is a genus ofspider mites.^[64]: 18 Three species are common on cotton here^[64]: 18 including thePacific Spider Mite (Tetranychuspacificus) and theTwo-Spotted Spider Mite (T. urticae).^{[300][64]: 18} and they are hard to distinguish because they aresympatric.^[64]: 18 Distinguishing them is nonetheless necessary, because they differ widely ininsecticide resistance, with the PSM the worst.^[64]: 18 The PSM and 2SSM are also significant in peach here.^[301] Two-Spotted Spider Mite is also a major pest of strawberry,^[302]

Cotton Aphids (Aphis gossypii, Melon Aphid) afflict cotton and melon crops here.^[303] Insecticides are commonly used, and this has producedresistance and may also contaminate theirhoneydew.^[303] Insecticide contaminated honeydew may harmbeneficial insects.^[303]

TheAvocado Thrips (Scirtothrips perseae) andPersea Mite (Oligonychus perseae) are twoinvasive pests here.^[19]

TheTobacco Budworm (Chloridea virescens,Heliothis virescens) is common on cotton in theImperial Valley.^[64]: 80 At least by 1985C. virescens had developedpermethrin resistance.^[64]: 80 Nicholson & Miller 1985 find severemetabolic resistance to permethrin in Imperial Valley populations.^[64]: 80

Western Flower Thrips (Frankliniella occidentalis) is a major pest ofhorticulturals around the world.^[304] Here, it is especially known as a pest of peach^[301] and strawberry.^[305][304]

TheDiamondback Moth (Plutella xylostella) is a commoninsect pest here.^[306]Btk (Bacillus thuringiensis kurstaki) is a commonly used insectide for Diamondback Moth control in California.^[306] Sheltonet al., 2000 finds a high degree of naturalgenetic variation inBtk resistance in the state's DM population.^[306]

SeveralAedes spp. are present.^[307]A. aegypti is found as anexotic pest here.^[308] Gloria-Soriaet al., 2016 finds a significant amount of shared genetics between the population ofthe southern part of the state andNew Mexico,Arizona, and Mexico.^[308]

Procambarus clarkii is aninvasive crayfish across theWestern US.^[309] It was first imported to afrog farm inSan Diego County in 1932, and proved so successful asfeed and food that descendants were sold around the state.^[309] They escaped and now are a widespread nuisance.^[309]

Lymantria dispar (spongy moth, gypsy moth) is anestablished pest here.^[310] Epanchin-Niellet al., 2012 find that annualsurveillance costs can be easily reduced.^[310] Costs are reduced by 50% by targeting surveillance resources based on the difference in surveillance cost by location, and by the difference inestablishment risk by location.^[310][311]

California red scale (Aonidiella aurantii) is aninvasive pest here.^[312] Itcompetitively displaced a prior invaderYellow scale (A. citrina).^[312] Debachet al., 1978 finds thatA. citrina is now extinct in this state due to the invasion ofA. aurantii.^[312]

TheBlack Vine Weevil (Otiorhynchus sulcatus) is mostly found in theCentral Coast AVA but does rarely occur elsewhere.^[313] Hosts include grape^[313] and strawberry.^[314] Creeping red fescue (Festuca rubra) is analternate host.^[313]

Otiorhynchus cribricollis (Cribrate weevil) is common in theSan Joaquin Valley.^[314] It is sometimes a problem in strawberry in the area.^[314]

Helicoverpa zea (syn.Heliothis zea) is common in several parts of the state including all strawberry growing areas.^[315]H. zea is especially troublesome in southern coastal California.^[315]

Cyclamen Mites occur natively here.^[316] Hosts include strawberry.^[316]

Scutigerella immaculata is anintroduced pest restricted to highmoisture soil.^[317] Hosts include strawberry.^[317]

Some slugs (Gastropoda spp.) are vegetable and fruit pests here.^[318] Several areintroduced pests from Europe.^[318] Hosts include strawberry.^[318]

European Earwigs are most destructive from April to July here.^[319] Hosts include strawberry.^[319]

Eotetranychus lewisi is found in coastal areas includingOxnard andSalinas.^[320] Hosts include strawberry.^[320]

Agrotis ipsilon is the most common cutworm here.^[321] Hosts include strawberry.^[321]

Pandemis pyrusana is present and eats the leaves of several crops.^[246] Hosts include strawberry.^[246]

Clepsis peritana is anecologically importantsaprovore.^[246] Later in the season it is a pest of strawberry.^[246]

Myzus persicae is present.^[322] Hosts include strawberry.^[322]

Macrosiphum euphorbiae is much larger than other aphids in California.^[322] Populations here have two forms, a green and a red.^[322] Hosts include strawberry.^[322]

Aedes albopictus is a pest of livestock concern.^[323] ModifiedWolbachia have been released to control this species here.^[323]

ThePink Bollworm (Pectinophora gossypiella) was devastating^[324] to cotton growers here and throughoutthe southwest.^[48] Chuet al., 1996 reports a management program in theImperial Valley in which government imposed practices successfully reduced populations.^[48]

Rejmanek & Pitcairn 2002 overview 53weed eradication campaigns in the state, and find that any infestation smaller than 2.5 acres (1.0 ha) was usually successfully eradicated, while anything which had already reached 2,500 acres (1,000 ha) was essentially impossible to do.^[325]: 137

Yellow Sweetclover (Melilotus officinalis L. Lam.),Chickweed (Stellaria spp.),Annual Bluegrass (Poa annuaLinnaeus),Shepherd's Purse (Capsella bursa-pastoris Linnaeus Medikus),Crabgrass (variousDigitaria spp.),Spotted Spurge (Euphorbia maculata Linnaeus Small), andYellow Nutsedge (Cyperus esculentus) are commonweeds here, including in strawberry and parsley.^[126] (See§ Strawberries, and§ Parsley.)

Marestail (Horseweed,Conyza canadensis,Erigeron canadensis) is a commonnative weed here.^[326]Glyphosate-resistant marestail first appeared in the state in theCentral Valley in 2005 and this resistance spread unusually rapidly through the southern Valley thereafter.^[326] Okadaet al., 2013 finds several independent evolutionary events, and that these unrelatedresistance alleles may have been passed along so quickly becauseC. canadensis can reproduce byselfing.^[326][48]Hairy Fleabane (Conyza bonariensis,Erigeron bonariensis) is one of the major§ Weeds in peach here.^[301] The Okada group also studiesglyphosate-resistant Hairy Fleabane.^[327] (See also§ Glyphosate.)

In theCentral Valley the most common weeds are cool-seasongrass weeds (Poaceae),thistles (Asteraceae),mustards (Brassicaceae),fiddleneck (Boraginaceae), warm-season grass weeds, warm-seasonCyperaceae,amaranths (Amaranthaceae),morning glory (Convolvulaceae), andcaltrop (Tribulus terrestris, Zygophyllaceae).^[328] Achmonet al., 2018 dramatically loweredseed bank viability,biomass, anddensity of all these weeds, and improved tomato yield usingbiosolarization using tomato and grape crop waste.^[328]

Cape-ivy (Delairea odorata) is aninvasive weed originally from theDrakensberg Mountains in South Africa and Swaziland.^[329] It was first observed here in 1892 and has since spread to every coast of the state, and into one coastal county ofOregon.^[329] Two organisms have been found in its native range which could be introduced here as controls, see§ Digitivalva delaireae and§ Cercospora delaireae.^[329]

Sea Beet (Beta vulgaris subsp.maritima) andBeta macrocarpa areintroduced weeds here.^[330][331] Theallozyme analysis of Bartsch & Ellstrand 1999 shows freegene flow between these two and cultivatedbeet.^[330] Wild beet is only significant in small grains inImperial, where dicamba and 2,4-D are necessary.^[332] See also§ Small grains.

Palmer Amaranth (Amaranthus palmeri) was first discovered inSan Diego County bySereno Watson in 1876.^[333] It has since spread elsewhere, developed the worstmultiresistance in the world, and become one of the most notorious cropweeds in the world.^[333] In California it is found in all but the northernmost counties.^[334]

California wild radish (radish (Raphanus sativus) × Jointed charlock (R. raphanistrum))^[335] has replaced all of its ancestral populations in the state.^[331]

Di Tomaso and Healy 2007 findChenopodium album requires years of continuousmanagement for any significantseedbank reduction.^[5]

X. fastidiosa was first discovered here byNewton B. Pierce (1856–1916) in 1892.^[336][337] It has ever since remained a constant pathogen of many crops here,^[338] including grape, almond, citrus, and oleander.^[119]

The CDFA'sPierce's Disease Control Program coordinates response and research in the state.^[339] Alstonet al., 2013 estimates that PD cost the state $92m in 2013^[340] and over Tumberet al., 2014 estimates $104m annually in 2014.^[257] Burbank estimates the cost to be $100m annually by 2022.^[341]

GWSS remains a common vector of PD and as such is a severe drag on the entire continent'swine grape andtable grape pricing and supply.^[252] In theNapa- andSonoma- Valleys and other such costal AVAs PD mostly occurs in hotspots adjacent to small water flows.^[258] These areas are defined by small streams and ornamental irrigation.^[258] These are favorable habitat for the BGSS.^[258] Linet al., 2005 provides SSRs for differentiating between the state's various strains infecting grape and other crops^[119] and Linet al., 2013 for grape-infecting strains here and in Texas.^[336]

The BGSS is known to thrive in higher temperatures and PD epidemics are more severe in hotter years, and there is evidence thatglobal warming is increasing BGSS transmission of PD here.^[342] Larger data sets are needed for stronger confirmation.^[342]

There are two major divisions here, a lineage fromBakersfield andSanta Barbara and another fromTemecula andthe north.^[343] Within the northern areas there is lowergene flow, probably due to theMayacamas Mountains.^[343]

Zhanget al., 2011 compares a PD strain toEB92-1 and finds that they are surprisingly similar.^[344] EB92-1 is abiocontrol strain discovered by Hopkins in 1992 and published as Hopkins 2005.^[344] It is originally from elderberry (Sambucus spp.) and is highly persistent on grapevine but isasymptomatic.^[344] Zhang finds that the EB92-1 genome is aproper subset of theTemecula1 genome, lacking 11 missinggenes, 10 of which arepredicted to bepathogenicity factors.^[344]

Vanhoveet al., 2020 elucidates the current genetic situation of PD strains here, includingpopulation structure andtheir evolution.^[345]

Xf is also significant in stonefruit here, causingAlmond leaf scorch disease and other diseases.^[338][336]Xf isolatesCFBP8071 andM23 are common on almond here.^[338] Moralejoet al., 2019 shed some light on the European invasion of this pathogen.^[338] Their analysis shows these isolates have a 99.4%nucleotide identity with those on grape in the introduced range – and more generally, these isolates, a Europeancherry infection, and PD isolates from both areas have a high degree of relatedness.^[338] Chenet al., 2005 providesPCR primers, Linet al., 2015Simple Sequence Repeats (SSRs), and Chenet al., 2010 the firstgenome sequence for common almond-infecting strains here.^[336] Linet al., 2005 provides SSRs for differentiating strains from almond from various other strains.^[119] While almond and plum developleaf scorch, Ledbetter & Rogers 2009 find that peach does not.^[336]

Besides Pierce's Disease, the glassy-winged sharpshooter also vectorsXf among stonefruit and so its arrival threatens the world's almond supply.^[252]

Linet al., 2005 providesSimple Sequence Repeats (SSRs) which distinguish California'sCitrus Variegated Chlorosis strains from almond, oleander, and PD strains.^[119]

Xf has many other hosts.Chitalpa tashkentensis is a commonlandscaping plant here and elsewhere in the southwest that is also a host.^[336] Randallet al., 2009 proposethe subspeciestashke for these strains but it remains unclear whether this is a distinct subspecies and whether it endures in the overall evolutionary course ofXf strains.^[336] Hernandez-Martinezet al., 2007 findthe subspeciessandyi causes disease of Oleander,Jacaranda spp.,daylily, andmagnolia.^[336]

Raju 1983 findsXf without symptoms on wildCarneocephala fulgida,Draeculacephala minerva, the Blue-Green Sharpshooter (BGSS,Graphocephala atropunctata, avector),Helocharadelta,Pagaronia tredecimpunctata, andPhilaenus spumarius.^[336] Purcell & Saunders 1999 find infections in plants common toriparian zones here often are not motile in the host and spontaneously improve.^[336]

Variousstrains ofgray mold (Botrytis cinerea) are a constant presence in the state'shorticulture, especially afflicting strawberry^[346] and grape.^[347]

Fungicides are used multiple times per seasons and as a resultresistance to almost everymode of action^[348] is common.^[346] Cosseboomet al., 2019 finds the proportion of resistant isolates increased within a single season inconventional but notorganic.^[346] This shows that evolution is driven by usage in this crop.^[346]

Alleles responsible include theerg27 allelesF196C,F412I, andF412S;bos1 allelesI356N,I365N, andI365S; theβ-tubulin alleleE198A (which Huet al. 2016 finds has nofitness penalty); thecytb alleleG143A (found by Veloukaset al., 2014 to have nofitness penalty); themrr1 alleleR351C and themrr1 deletion eventΔL497 (also known asMDR1h and found only inBotrytis group S); andsdhB allelesH272R,H272Y,N230I, andP225F (the only one conferringresistance to isofetamid,also confers other resistance –to penthiopyrad,to fluopyram, andto boscalid – and associated by Huet al., 2016 withresistance to fluxapyroxad).^[346] The analysis of Cosseboomet al., 2019 explains 93.8% of resistance by already-known alleles discovered by Bannoet al., 2008, Maet al., 2007, Grabkeet al., 2013, Kretschmeret al., 2009, Dowlinget al., 2017, Fernández-Ortuñoet al., 2012, Amiriet al., 2014, and Yinet al., 2011, so very little is due to experimental error, unknown physiological effects, or undiscovered alleles.^[346]

Organic strawberry ranches experience very active genetic transfer with conventional strawberry and as a result they have high proportions of resistance.^[346] Cosseboomet al., 2019 finds that conventional fields undergo within-seasonresistance evolution, while organic does not, demonstrating that they are indeed not using the fungicides they claim to not use, and that genetic transfer is not so rapid as to change the situation in a field that quickly.^[346]

Ma & Michailides 2005 developed amicrosatellite primed PCR (MP-PCR) forgenetic diversity in this fungus, especially for populations in this state.^[349]Strawberry Botrytis leaf spot was first discovered in 2018 inSanta Maria and reported by Mansouripour & Holmes 2020.^[350]Bc was not previously known to produce aleaf spot phenotype in strawberry.^[350]

In table grape there is a limit of 0.5% – table grapes can only be shipped if an allotment contains 0.5% or less ofBc-infected berries.^[347] Ozone is one treatment option for grape.^[347]

Shaoet al., 2021 findazoxystrobin resistance is very common in thispopulation.^[351] They find it is much more common than in China where azoxystrobin is almost unknown.^[351]

B. cinerea is a common cause ofpostharvest losses in this industry.^[352] Due to the need for longshelf life in the California industry – because target markets include the whole continent – and the low moisture growing environments, Petraschet al., 2021 findgenomic selection for strawberry resistance is highly successful.^[352] In other environments and markets however this is not expected to be as simple.^[352]

MostB. cinereainoculum is introduced viaaeroplankton.^[353] Significant protection against this is afforded bypolytunnels.^[353] Daugovish & Larson 2009 find 84%–90% greater yield and 62%–140% greatermarketable yield resulting in $14,000–$18,500 per hectare ($5,700–$7,500/acre) greater revenue due to polytunnels.^[353]

Though gray mold elsewhere may be caused by bothB. cinerea andB. pseudocinerea in CaliforniaB. pseudocinerea is unknown on strawberry.^[354] However it is found on blueberry in the San Joaquin Valley.^[354]

Red Blotch Disease (caused bygrapevine red blotch virus, GLRaV-3^{[citation needed]}) costs the state $90 million annually.^[340] Losses inNapa County cost over $69,500 per hectare ($28,100/acre) across the likely 25-year lifetime of a vineyard, far higher than the $2,200 per hectare ($890/acre) estimated foreastern Washington.^[340]

Al Rwahnihet al., 2013 discoveredGrapevine Red Blotch-associated Virus (GRBaV) here, a DNA virus of this crop.^[355][356]

Leafroll Disease (grapevine leafroll-associated virus 3) is also economically significant.^[340]

The seriousness ofPowdery Mildew (Uncinula necator) has been recognized since at least 1859 in the northern grape district.^[357]Newton B. Pierce was working in the area a few decades before his discovery of Pierce's Disease, and over the 1860s he watchedU. necator spread to the south.^[357]Frederic Bioletti called it the onlyserious fungal disease the industry suffered from, and so it has remained ever since.^[357][358] The first case ofU. necatordemethylation inhibitor resistance (DMI resistance) was found in this state in 1980.^[359] This was only confirmed with Gubleret al., 1996's reanalysis of 1986 and 1990 samples however.^[359] Gubler finds that reduced rates prescribed by IPM are responsible for some ofU. necator'striadimefon-,myclobutanil-, andfenarimol resistances.^{[134][360][359]}

Phomopsis dieback (caused byPhomopsis viticola) is also a major trunk disease here.^[356] It isendemic to California.^[356]

Fusarium is a genus of manyspecies which are ubiquitous around the world, including here.

Fusarium Wilt of Strawberry (Fusarium oxysporum f. sp.fragariae) had only been seen once before, inQueensland, in one sample of Winks & Williams in 1966,^[361] until appearing again here in 2006 and identified by Koikeet al. 2009.^[362] As of 2018^[update] it has spread throughout the state.^[363] Henryet al., 2017 apply a JapanesePCR-based test of nuclear ribosomalintergenic spacer andelongation factor 1-α.^[364] They find such high similarity between the intended – Japanese – target populations and California populations that there are almost nofalse negatives.^[364] There are nofalse positives on otherFo types (i.e. those not pathogenic on strawberry).^[364] Although this suggests both populations have a common origin, that remains to be proven. The matching IGS and EF-1α sequences divide into threesomatic compatibility groups.^[364] The vast majority fell into what they term SCG1, with a few of SCG2 and SCG3.^[364] SCG2 is always a false negative with this test which may indicate the entire group lacks the sequence in question.^[364] Although this proves to be a good test, a universally valid test may require finding a sequence specifically pertinent tovirulence on the host and not other, incidental sequences.^[364]

In early 2012 a previously unknownplant disease (an unidentifiedFusarium) andvector (aEuwallacea, preliminarily termed thepolyphagous shot hole borer, PSHB) were detected inLos Angeles andOrange Counties.^[18] This is especially a disease affecting avocado growers, but also other crops in this state and in its other invasive range,in Israel.^[18] In fact although PSHB was noticed on ablack locust here in 2003, the associatedFusarium was only detected in 2012 on home avocado trees inLA County.^[18] As allEuwallacea in both their native and invasive ranges, this insect prefers to infest hosts in this area in locations which are stressful due to their unnaturalness, such as urban ornamental plantings andorchards.^[18]

Fusarium Wilt of Lettuce (Fusarium oxysporum f. sp.lactucum) is common in the state.^[365]

Fusarium oxysporum f. sp.vasinfectum is a disease of§ Cotton.^[366] Kimet al., 2005 finds races 1, 2, 3, 4, 6 and 8 are present.^[366] They find race 4 arrived fromIndia in 2003.^[366] Race 4 is so common here that varieties are screened for resistance before development or deployment.^[367] Unlike otherstrains it does not require avector, aroot-knot nematode.^[368] Race 4 isolates here are morepathogenic onGossypium barbadense than onG. hirsutum.^[369]

VariousAlternaria spp. are significantfungal diseases here and often receivestrobilurin,iprodione,azoxystrobin, andtebuconazole treatments.^[146] The Ma & Michaelides group has done extensive work onfungicide resistance, including in these pathogens.^[146] They have characterizedresistance alleles (and in some cases producedmolecular diagnostics methologies) forstrobilurin-resistant-,iprodione-resistant-, andazoxystrobin-resistant- isolates.^[146]

A. alternata has one of the widest host ranges of anyfungal crop pathogen and so fungicides are commonly used.^[370] Almost all fruiting production of vulnerable crops must be fungicide-treated.^[370] Avenot, along with the Michailides group has found extensiveboscalid resistance in a swathe from the center down into the central southern part of the state, especiallyKern,Tulare,Fresno, andMadera.^[371][370] Although it is also commonlyapplied inKings, no resistance is known there.^[370]

Black Heart is a common pomegranate disease worldwide. Out of the group of causative species, here Luoet al., 2017 find it is caused byA. alternata andA. arborescens.^{[45]: 192 [372]} Michailideset al., 2008 finds the'Wonderful' cultivar can suffer at a rate of 10% or more here.^{[45]: 192 [373]: S105}

Alternaria Rot of Fig is common here. It is caused by various species of this genus and relatives including:Ulocladium atrum,A. alternata, rarely otherAlternaria spp.,Dendryphiella vinosa, andCurvularia spp.Epicoccum purpurascens causes Alternaria of breba only.^[374] (The first, "breba" crop is not eaten but must be removed because it harborsinoculum of all of these microbes for the second, real crop.)^[374]

ThePeach Yellow Leaf Roll phytoplasma (Candidatus Phytoplasma pyri) was first found here in theSacramento Valley in 1948.^[375] The samepathogen may be the cause ofAlmond Brown Line and Decline.^[375]

Phytophthora cactorum causesStrawberry crown rot, a common disease here.^[376]

TheFoliar Nematode (Aphelenchoides fragariae) andNorthern Root Knot Nematode (Meloidogyne hapla) are the two most commonstrawberry nematode diseases here,^[377] although RKN is rarely seen by CalPoly Strawberry Center's diagnostic lab.^[378] Even rarer are theRoot Lesion (Pratylenchus penetrans),Stem (Ditylenchus dipsaci),Dagger (Xiphinema americanum),Needle (Longidorus elongatus),Foliar (Aphelenchoides ritzemabosi andA. besseyi), and otherRoot Knot (Meloidogyne incognita andM. javanica) nematodes.^[377]

Anthracnose occurs onpeach,almond, andstrawberry here.^[379]Colletotrichum acutatum – asoilborne pathogen^[380] – is a common cause.^[379] Natamycin is often used in strawberry.^[379] Adaskaveg & Hartin 1997 identify theC. acutatumstrains most frequently responsible in peach and almond.^[379]

Monilinia fructicola andM. laxa are significant diseases of stonefruits here andbenzimidazole is often used.^[146] The Ma & Michaelides group has done extensive work onfungicide resistance in these microorganisms.^[146]

Botryosphaeria dothidea is a significantfungal diseases here which often receivesstrobilurin,iprodione,azoxystrobin, andtebuconazole treatments.^[146] The Ma & Michaelides group has done extensive work onfungicide resistance, including in this pathogen.^[146] They have characterizedresistance alleles oftebuconazole-resistant- isolates.^[146]

Figs commonly suffer fromFig Smut here.^[374] Smut is caused by variousAspergillus spp. and relatives, including:Aspergillus niger,A. japonicus,A. carbonarius,A. flavus andA. parasiticus,Eurotium spp.,A. tamarii,A. terreus,A. wentii,A. alliaceus,A. melleus,A. ochraceus,Emericella spp.,A. carneus,A. fumigatus,A. sclerotiorum, andA. sydowii.^[374]

Olives here suffer from a wide range offungal diseases of theBotryosphaeriaceae family, as elsewhere in the world.^[122] Úrbez-Torreset al., 2013 findsNeofusicoccummediterraneum andDiplodia mutila are the most virulent of them onManzanillo andSevillano.^[122] Moralet al., 2010 findsN. mediterraneum commonly causes abranch blight on several cultivars andD. seriata causes abranch canker.^[122] More specific controls than currently available are needed forN. mediterraneum in highly susceptible cultivars, and early harvest may be the only successful treatment forD. seriata.^[122]

Avian malaria is present in the state.^[185][184]Plasmodium relictum and itsvectorsC. quinquefasciatus,C. stigmatosoma, andC. tarsalis are most commonly responsible.^[184]

Stripe Rust (Puccinia striiformis f. sp.tritici,Pst) is found onBarley, wheat, and various grasses here.^[20]: 9 Maccaferriet al. 2015 surveys the world's wheat and finds theDavisPst populations are unusually heterogenous.^[381] That makes the Davis environment a useful experimental location for differentiating wheatgenetic resistance.^[381]

Stromatinia cepivora (garlic white rot) was identified in theSan Francisco area in the 1930s andGilroy in the 1940s.^[382] It continues to be a problem for garlic growers in the state.^[383]

Leaf Spot of Caneberry (Mycosphaerella rubi, anamorphSeptoria rubi) is common here.^[26] It is common on caneberry excluding raspberry, so erect and trailing blackberry, dewberry, olallieberry, and boysenberry.^[26] Treatment is simple, almost entirely relying on increased air circulation.^[26] Nofungicides are registered but any fungicides for§ Anthracnose and§ Gray mold will work.^[26]Copper andlime sulfur work to some degree.^[26]

This should be distinguished fromLeaf Spot of Raspberry (Sphaerulina rubi, anamorphCylindrosporium rubi).^[26] Although Leaf Spot of Raspberry is found here it is notcommon in California.^[26]

Verticillium Wilts (biovars ofVerticillium dahliae) are found here as in any other ecozone. This includesVerticillium Wilt of Strawberry.^[384] Unlike every other known Vert Wilt of any other crop, this syndrome sometimes lacks any or any noticeablevascular discoloration of thecrown.^[385] In strawberry, methyl bromide has historically been vital to prevention, and with phase out, this disease is of increasing concern.^[384][386] In all casessome fumigation is necessary, and if fumigation is not possible then solarization and/orrotation are the only remaining options.^[384] Althoughdrip fumigation (fumigation inline in thedrip tape) is possible it does not produce the same results, especially failing to reach the shoulders of the beds.^[384] Nurseries universally use MB or MB + chloropicrin, while growers may use 1,3-D + chloropicrin, chloropicrin alone, metam sodium, or metam potassium.^[384] Note that MB+chloropicrin also provides an uncharacterizedgrowth promoter effect in this crop.^[386]: 180

Strawberry Crinkle Virus (SCV,Strawberry crinkle cytorhabdovirus) is common here.^{[387][388][389]} Much of the fundamental research into SCV has been performed by a lab atUC Berkeley, including research onmechanical transmission.^[387][388]

Frequent use has producedstreptomycin resistance inFire Blight (Erwinia amylovora) here,^[390] first found in the state's pearisolates by Miller & Schroth 1972.^[135] This disease is a problem of pomes, including pear.^[390]

Podosphaeraaphanis is the cause of powdery mildew of strawberry.^[391] It hasevolved strong resistance here.^[391] Palmer & Holmes 2021 find resistance to the majority of the most commonly applied ingredients in theOxnard population.^[391]

Armillaria Root Rot of peach is primarily caused byArmillaria mellea andA. solidipes here.^[392]A. gallica andA. mexicana are not thought to be common here, but are common in Mexico.^[392]

Tomato infectious chlorosis virus afflicts tomato here.^[393]: 180

16SrIII-A is aphytoplasma of apricot here.^[394] Uyemotoet al., 1991 found it on apricot in California.^[394]

Downy Mildew of Lettuce (Bremia lactucae) is common on lettuce here.^[395]: 156 The population in the country, and especially in this state, is unusual however: It is highly clonal.^[395]: 156 As a result, Brownet al., 2004 finds allisolates have the samemetalaxyl resistance.^[395]: 156

Kimet al., 2015 findsPenicillium digitatum isolates from citrus here have developed fludioxonil resistance,^[396]Thiabendazole (TBZ) is also commonly used in citrus here.^[397] Schmidtet al., 2006 findpoint mutations atcodon 200 conferringTBZ resistance are common in California.^[397]

Karnal Bunt (Tilletia indica, syn.Neovossia indica) has spread from Asia to this continent, and since 1996 has been found in this country.^[398]: 592 It is present in areas of this state, andArizona andTexas.^[398]: 592

Corn Stunt Disease (Spiroplasma kunkelii) affectscorn (maize,Zea mays) here.^[399]

Sudden Oak Death (Phytophthora ramorum) is a widespread disease of oaks here and in Oregon, and is also found in Europe.^[117] It was first discovered in the 1990s on theCentral Coast^[400] and was quicklyfound in Oregon as well.^[401]P. ramorum is of economic concern due to its infestation ofRubus andVaccinium spp.^[401] Allisolates here and throughout North America have been of theA2 mating type andgenetic analysis suggests that although it was discovered here, the pathogen originated elsewhere.^[401]

Phytophthora fragariae is a common disease of strawberry here.^[402] Weg 1997 shows that theresistance geneRpf1 is in agene-for-gene relationship.^[402] Mathey 2013 shows thatRpf1 is responsible for most resistance in the Watsonville and Oxnard environments and provides a DNA test to predict performance.^[402] No tests are available forPhytophthora fragariae var.fragariae.^[389] FPS recommends diagnosis by visual inspection.^[389]

Apple mosaic virus,Arabis mosaic virus andTomato ringspot virus are common pathogens in strawberry.^[403]

Raspberry ringspot virus is a common pathogen in California.^[389] Diagnosis is performed by cross infection of one of thealternate hosts which areherbaceous.^[389]

Strawberry feather leaf virus is a common pathogen.^[389]Foundation Plant Services (FPS) offers testing via leaf graft.^[404]

Hosts ofStrawberry latent C virus include strawberry.^[389]

Strawberry latent ringspot virus is diagnosed by cross infection of one of thealternate hosts which areherbaceous or bypolymerase chain reaction (PCR).^[389]

Strawberry leaf roll disease is a common pathogen.^[389]

Strawberry mild yellow edge virus is diagnosed by cross infection of a test strawberry or bypolymerase chain reaction (PCR).^[389]

Hosts ofStrawberry mottle virus include strawberry.^[389]

Strawberry pallidosis associated virus is diagnosed by cross infection of a test strawberry or bypolymerase chain reaction (PCR).^[389] It is one of several viuses causingPallidosis Related Decline of Strawberry.^[405]: 68

Diagnosis ofStrawberry vein banding virus is performed by cross infection of an herbaceous alternate host or by PCR.^[389]

Tobacco necrosis virus is diagnosed by cross infection of an herbaceous alternate host.^[389]Biosecurity Australia considers its presence here cause for concern for Australian stonefruit growers.^[406]

Hosts ofTobacco streak virus include strawberry.^[389]

Diagnosis ofTomato black ring virus is performed by cross infection of an herbaceous alternate host.^[389]

Tomato bushy stunt virus is a common pathogen of severalhorticultural crops here.^[389]

Tomato ringspot virus is diagnosed by cross infection of an herbaceous alternate host.^[389] Hosts include strawberry.^[407]

Hosts ofXanthomonas fragariae include strawberry.^[389]

Aphelenchoides besseyi is a common horticultural nematode disease in California.^[389]

Barley/Cereal yellow dwarf virus (B/CYDV) harms nativebunchgrasses more than aninvasive grass, aiding the invasion.^[408]

Tomato necrotic dwarf virus is originally known fromImperial County.^[409]

More than 1 virus is usually present in any strawberry plant which has progressed tosymptomatic infection.^[410]

Lettuce Mosaic Virus has caused severe losses at times up to 100%.^[411]: 282

As with the entire country there isUSDA subsidizedcrop insurance for the state.^[412] TheRisk Management Agency provides various insurance schemes and deadlines byCounty and by crop.^[412]

Foundation Plant Services^[413] (FPS) is a part ofUCD's College of Agriculture which serves thehorticultural industries. FPS performs several services including testing fordiseases (especiallyviral diseases), identifyingvarieties of unknown plant samples, and supplying cuttings (vegetative propagation material) fromin situ individuals they maintain.^[413] They use a library of publishedSimple Sequence Repeats (SSRs) known to be relevant to the state's strawberry industry to identify those varieties specifically.^[376]California Seed & Plant Lab is an even more active, private molecular lab for the strawberry industry.^[376] CS&PL tests for clients here and around the world.^[376]

California's experiences with the Vine mealybug, Glassy-winged sharp-shooter, and Pierce's disease have informed the process of creatinggeographic models for the spread of pests and diseases and their management inviticulture around the world.^[414]: 43 See§ Glassy-winged sharpshooter and§ Pierce's Disease.

As of 2022^[update] Professor Juan Pablo Giraldo (UCR) has been making great progress since 2013 innanomaterials applied to crops.^[415][416]

TheUniversity of California is one of the two institutions claiming ownership of theCRISPR/Cas9 patent.^[417] This technique has great promise for genetic improvement of agricultural organisms.^[417] What ever the outcome of thepatent litigation, alicense from UC or theBroad Institute or both may be required to produce such products in the future.^[417]

TheUC Davis Farm Labor program studies the state's farmworkers and provides information about them.^[418]

Theunion organizing campaign ofCésar Chávez and its impact on the industry has become a well known chapter in American history.^[419]: 63 His movement was also joined byartists such as famed theater and film directorLuis Valdéz.^[420]: 92Ecofeminists have supported theUnited Farm Workers' strikes including Chávez'sGrape boycott, especially for their positions on pesticides.^[421]

Despite theImmigration Reform and Control Act of 1986, Taylor & Thilmany 1992 found that the state's farmers did not reduce their hiring ofillegal immigrants as farmworkers.^[422] Indeed, illegal immigration inflows increased in the 1990s.^[423]

In addition to advising producers, the Statewide Integrated Pest Management program (UC IPM) began training farmworkers in 1988.^[424]: 382

By the late 1990s the large immigrant population had expanded theworkforce, reducedwages andworking time per worker.^[425]: 122 The reanalysis of Khanet al., 2004 finds that increased production of labor demanding crops increases agriculturallabor demand, but does not necessarily have to because the same workers could have been hired to perform more hours.^[426] For many decades theImmigration and Naturalization Service (INS) andCustoms and Border Protection (CBP) left farmworkers alone.^[427] INS and then CBP chose not to do any significant enforcement in agriculture,hospitality, orconstruction.^[427] Especially in theNorthern Sacramento Valley andSouthern San Joaquin Valley, farmworkers had risen to a highproportion of the population by 2013.^[428]

The broader implications of intensified immigration enforcement are significant. The U.S. agricultural industry relies heavily on immigrant labor, with undocumented workers comprising a substantial portion of the workforce. In California, estimates suggest that undocumented immigrants make up about 70% of the state's agricultural workers.^[429]

Despite the passage of theCalifornia Agricultural Labor Relations Act of 1975, by 2012 unions were less popular with farmworkers than they had been before it was passed.^[430]

The Borello 1988 decision classifies strawberry sharecroppers asindependent contractors.^[431]

Even when immigration was unrestricted, strawberry growers felt in 2017 thatlabor supply was still too tight.^[432] Farmers here were solid supporters of candidate and thenPresident Trump, but were quickly surprised by the rhetoric of the administration due to the labor situation in the industry.^[433] As late as 2017 the illegal workforce was stillprojected to grow.^[434] APew Research Center analysis by Passel & Cohn expected continued lax enforcement to produce a continued population boom, including among California's agricultural workers.^[434] During and after the escalateddeportation raids the lack of normal labor opened opportunities for others.^[435] Many high school students with farmworker family members quit school to join them in the fields.^[435]

Somefarmworkers here are not employed here all year but instead travel to other agricultural employment while California is in the off season.^[436]

Although the entire tomato harvest was performed by laborers until recently, machines for harvest have been developed.^[437] The harvest of processing tomatoes is now entirely done by machines.^[437] The fresh tomato market still must be supplied by laborers however.^[437] See§ Tomatoes. Just before the 2018 deportations began, in 2017strawberry pickers earned ~$150/day or ~$18.75/hour.^[438]

The rightpersonal protective equipment is required for fumigant applicators and those working nearby.^[439] Practices and training and provided by thestate Department of Pesticide Regulation.^[439]

As of 2019^[update], 9% of allunauthorized immigrants in California are employed in this industry.^[440]

Enforcement of state laws and regulations regarding farm labor and pesticides is the responsibility of theCounty Agricultural Commissioners.^[441]: 19

Harrison & Getz 2015 studyorganic fruit and vegetable workers here and find that working conditions generally improve with increasing farm size.^[442] Stocktonet al., 2017's meta analysis shows workers were earning two-thirds of the averageCalifornian due to a combination of low wages andunderemployment.^[443]

Hundreds of thousands of members of native Mexican ethnics are estimated to live in the state as farmworkers.^[444]

The stateDepartment of Industrial Relations (DIR)^[445] regulates and provides information for workers and employers. DIR'sLabor Enforcement Task Force (LETF) enforces such requirements asovertime.^[446] UCANR and UCCE also provide information for employers' business planning.^[447]