The 2020 table grape harvest was worth $2.12 billion while wine grapes brought in $1.7 billion, down 15.3% year-on-year. By weight, this was 17% lower versus 2018. The next year, 2021 saw a much better yield. From viniculturists got for a total harvest of . At an average of they were paid $5,229,902,000 for the season. Of that, were for destined for processing industries (including wine, see below) and at that was worth $4,046,382,000. The fresh (table grape) harvest was and selling at a price of , this sector was worth $1,183,520,000 for the season.
The table grape and wine grape sectors are represented by the and the California Association of Winegrape Growers.
Table production is most concentrated in three counties and somewhat in another two. Dollar value annually is $1,240 million in Kern, $682 in Tulare, $416 in Fresno, and in the top ten crops in Riverside and Madera. California's own consumption of table production grew from 1980 to 2001 from per capita per year. Consumption here and throughout the country is so high that the country remains a net importer despite this state's production, which reached in the 2015 table harvest.
During dormancy, UC IPM recommends pruning. UC IPM publishes recommendations for this and other tasks during dormancy. Although thinning is often proven to improve wine qualities in many areas, some reviewers note a lack of benefit in thinning table grapes in this state's vineyards.
Deyett et al., 2020 finds Proteobacteria are the most common components of the microbiomes of this crop in this state's soils.
This crop has also played a large part in farm labor relations in the state. The Delano grape strike began among table grape workers before spreading to other industries. See .
Diseases of grape Disease information is provided by UC IPM.
Xylella fastidiosa was first discovered here in 1892 when Newton B. Pierce found Pierce's Disease in Los Angeles. Today it costs the state an estimated $100m per year. Because Vitis species native to the USA are tolerant to PD while the introduced European V. vinifera is very susceptible, Hewitt 1958 posited the Gulf Coastal Plain as the center of origin for the pathogen. However Nunney et al., 2010 demonstrates that the PD population of the USA is originally in Central America. Sisterson et al. 2020 finds that the southern San Joaquin Valley rarely has any X. fastidiosa prior to July. This suggests an entirely Glassy-Winged Sharpshooter vectored problem that has no (or very little) overwintering capacity. Consistent with this they also found that neonicotinoid applications tended to reduce PD incidence. See also , and for a treatment see .
Al Rwahnih et al., 2015 finds widespread Grapevine red blotch-associated virus (GRBaV) among raisin and table accessions of propagation material in California. The virus population here has an unusually low amount of genetic diversity. Although not known outside of North America, Al Rwahnih et al. does find this virus in California material originating outside North America. See .
UCD's FPS performs disease testing, vinestock identification testing, and supplies vinestock. FPS is one of the few National Clean Plant Network (NCPN) members holding vinestock for grapes in the country. See also .
The Canadian Food Inspection Agency has a good opinion of the state's phytosanitary certification system. As a result, CFIA's Plant Protection Division has approved California plant material for import.
Hoffman et al., 2011 surveys the Lodi AVA and finds that growers themselves (including those who also work as educators for other growers) are most central to the spread of management information. Those who are not themselves growers, but are full time educators, are less connected to the actual spread of information.
(Uncinula necator) is another costly disease here. PM cost the industry $239 million in 2015, including losses and treatment costs, according to the estimate of Sambucci et al., 2019. For decades both the programs of USDA ARS and have prioritized breeding for resistance to this disease.
Afflictions in grapevine around the world are often treated by removal and replanting, and this is often used in this state's industry. Regrowth is slow and replant disease often results from this. Westphal et al., 2002 finds that regrowth is hampered by the soil microbiome in California's soils. They apply a supplemental plant growth-promiting rhizobacteria (PGPR) treatment using arbuscular mycorrhizal fungi (AMF) and achieve quicker productivity recovery. This is one of the few studies in this technique and this area is understudied.
It is speculated that drought stress will increase fungal pathogen geographic range in the future around the world, but in this state this has already been observed.
Although famous for its devastation of strawberry gray mold affects table grape as well. Karabulut et al., 2003 finds it is an especially large part of post-harvest losses. They also describe common treatments and make recommendations See and for a treatment see .
s are common in California. They are not caused by any one pathogen but are united by their similar symptomology in this part of the grape plant.
diseases are common trunk diseases. In the southern parts of the state, a Botryosphaeria Dieback caused by Lasiodiplodia theobromae is almost always the only trunk disease in this crop.
is another common trunk dieback here, caused by . It was first found here by English et al., 1962 a few years after its discovery elsewhere. Travadon et al., 2011 finds that E. lata is an entirely or almost entirely sexual population here but asexual reproduction may be a rare occurrence.This review cites this research. E. lata populations in California are shared between three hosts, this one, apricot and willow (Salix spp.). Travadon et al. 2015 finds high gene flow and an absence of differentiating alleles between populations on these hosts. (See also .) Additionally they find no differentiation by geography.This review cites this research.
(the California Dagger Nematode, or just Dagger Nematode) is a common disease here. Although first discovered in this state it has spread throughout the world's vineyards.
(Measles, Spanish Measles, Black Measles) is a basidiomycete disease caused by several species of the Fomitiporia. It is a common cause of economic loss in the state. Vasquez 2007 assessed losses for all afflictions called "Esca" in the state's vineyards.
(GPGV) was imported in infected 'Touriga National' in 1981 and maintained at UCD, but no epidemic has ever been documented from that contamination. The California epidemic began decades later. Al Rwahnih 2018 documents an active epidemic in the Napa Valley AVA and finds wide variation in occurrence per variety, from 8.7 to 100%.
Pests of grape For insect pests see (GWSS) and (BGSS).
The arrival of the European Grapevine Moth (EGVM) in Napa County in 2009 brought together local, state and federal agricultural officials, scientists in California universities, and the wine, table and raisin industries. Together they brought about an eradication by 2015 and the effort was declared a success in August 2016. There is ongoing concern that it will invade again. Gutierrez et al., 2012 finds that climate change has increased its potential invasive range on this crop in the time since its eradication, and will continue to do so. See .
Some vertebrate pests are also significant and UC IPM has management recommendations for them: Birds California Ground Squirrels (Otospermophilus beecheyi) Deer Pocket Gophers Rabbits Voles, especially the (Microtus californicus) Meadow Voles (Microtus drummondii) Meadow Mice (Microtus pennsylvanicus)
Delayed-dormancy in table grape varieties is February in the San Joaquin Valley and December to January in the Coachella Valley. UC IPM provides sampling techniques and management information for delayed-dormancy in table grape.
Budbreak is in March in the SJV and January to February in the Coachella Valley for common table varieties. UC IPM provides monitoring and treatment information for budbreak.
The rapid shoot growth phase is March to May in the San Joaquin Valley and February to May in the Coachella Valley. UC IPM recommends looking for spider mites and their natural enemies at this time. See .
During postharvest in the SJV, table grape growers should monitor for (Parthenolecanium corni). UC IPM provides information on this and other pests of postharvest in table grape. They recommend some parasitoids for biological control including Aphytis spp., Coccophagus spp., Encarsia spp., and Metaphycus luteolus.
Its anticipated damage to this crop was one of the major reasons for the passage of the LBAM Act of 2007. Despite expectations, this crop was not sufficiently impacted to justify the cost and controversy involved and the action is regarded as a failure. See .
The (Harrisina metallica, syn. H. brillians) is a native pest of this crop. The parasitoids and were imported in the 1950s but without success. However A. misella was found in the 1990s to be a vector of a granulovirus of this pest. cites WGS is multivoline, trivoltine in the Central Valley and bivoltine on the coasts because temperatures are lower.
The (Planococcus ficus) (Signoret (Homoptera: Pseudococcidae)) is a pest introduced in the early 1990s. It has spread quickly, impacting vine culture due to its phloem-feeding habit and because it is a vector of GLRaV. See also .
Thrips are a minor concern in wine and raisin but are significant pests in table varieties. This includes (Drepanothrips reuteri) and Western Flower Thrips. The scarring that they cause defaces the appearance of table grapes. Grape Thrips in Salvador is especially problematic. See .
Five species of are significant in this crop: s (Linepithema humile), s (Formica aerata, Formica perpilosa), (Tetramorium caespitum), (Solenopsis xyloni) and (Solenopsis molesta).
The Black Vine Weevil is mostly a pest of the Central Coast AVA but does rarely occur elsewhere. Treatment is possible but is usually not employed. See .
(Argyrotaenia franciscana) is a native pest of this crop. It is endemic to this state and Oregon and Washington. UC IPM recommends restricting use of insecticides to control Orange Tortrix because many natural biological controls are present in the state.
mealybugs are common pests in California's vineyards. They have become an increasing problem in the first half of the 2010s. Three species are present: (P. maritimus), (P. longispinus) and (P. viburni).
Phylloxera of Grape is a common aphid in California with multiple subpopulations derived from multiple foreign points of origin producing multiple invasions. The rootstock AxR#1 was formerly used due to its resistance but this has since collapsed and been replaced by other rootstocks. This phylloxera has since that time adapted to these various rootstocks. Corrie et al., 2002, Lin et al., 2006, Vorwerk & Forneck, 2006 develop microsatellite markers to track these multiple invasions and their adaptation. See and .
Breeding of grape This state has the largest breeding program for table grape in the country. The next largest is at the University of Arkansas, and that was started in part from varieties developed here. Many widely used table varieties have been developed here, such as '' and 'Red Globe' from Harold Olmo at UCD, and the 'Flame Seedless' in 1973 and '' in 1994 by the USDA program in Fresno.
Although there is some resistance to Pierce's Disease in some Vitis vinifera varieties, none is immune none will be productive and all will die. The Walker group at UC Davis has discovered several monogenic and polygenic PD resistances in several other Vitis spp. A few years later in December 2019, their , , , , and were plant patented and released for licensing.