Grape cultivation in California
[6] 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.
[14] 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.
[15]: 97 Sisterson et al. 2020[16] finds that the southern San Joaquin Valley rarely has any X. fastidiosa prior to July.
Al Rwahnih et al., 2015 finds widespread Grapevine red blotch-associated virus (GRBaV) among raisin and table accessions of propagation material in California.
[19][20] FPS is one of the few National Clean Plant Network (NCPN) members holding vinestock for grapes in the country.
[27] They apply a supplemental plant growth-promiting rhizobacteria (PGPR) treatment using arbuscular mycorrhizal fungi (AMF) and achieve quicker productivity recovery.
[27] 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.
[31] In the southern parts of the state, a Botryosphaeria Dieback caused by Lasiodiplodia theobromae is almost always the only trunk disease in this crop.
[30] Grapevine Pinot gris virus (GPGV) was imported in infected 'Touriga National' in 1981 and maintained at UCD, but no epidemic has ever been documented from that contamination.
[36] 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%.
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.
[40] 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.
During postharvest in the SJV, table grape growers should monitor for European Fruit Lecanium Scale (Parthenolecanium corni).
[48] Despite expectations, this crop was not sufficiently impacted to justify the cost and controversy involved and the action is regarded as a failure.
Fuller et al., 2014 finds Powdery Mildew resistance in grape (Erysiphe necator) is so valuable in the state's AVAs and the technique of blending has so improved that PM-resistant type are becoming increasingly adopted, despite their history of consumer rejection due to off flavors.
[67] Fuller et al. 2014 also find that widespread adoption of such varieties would save growers as much as $48 million/year in California's Crimson Seedless table, raisin and Central Coast Chardonnay vineyards alone.
[72] Their work includes incorporating wild North American V. arizonica and V. candicans into seedless raisin and table varieties.
[74] Then in 2019 they released 5 with high PD resistance to combat a problem which costs California grape growers over $100 million per year.
[77] Bowers et al., 1999 develops some of the foundational microsatellite markers for breeding of California Pinot noirs and Cabernet Sauvignons.
[79] This develops a standard of microsatellites for California's most common vinestock and rootstock varieties to aid identification in breeding programs.
[80] Vignani et al. 1996 demonstrates that several cultivars long grown in California, and thought to be local innovations, are instead clones of several Italian varieties.
[62] As of 2014[update] several candidate genes have been identified, several have been transferred, and some even produce immune factors that cross the graft union and so can be rootstock-only.
Zakowski & Mace 2022 finds heavy use of fungicides for cosmetic reasons in the state's table grape industry.
The General Beale Pilot Project has been very successful since the early 2000s in monitoring and reducing the deadly disease and vector combination of PD and GWSS.
[90] The campaign in Kern is a good model for the whole world's efforts against this threat,[89][90] and for farmer funded voluntary management programs in general.
[93] Costello & Daane 1998 finds that ground cover in table grape increases Trachelas pacificus abundance but decreases Hololena nedra.
[93] UC IPM recommends considering the impact of a pesticide application on natural enemies and honey bees before applying to table vineyards.
[94] Crab shell chitosan reduces postharvest Gray Mold in table grape in Fresno county.
[95] By dissolving the shell material in an acid they achieve control of postharvest Gray Mold by inducing a defense prior to the fungus's invasion.
[95] Karabulut et al., 2003 finds that many postharvest pathogen isolates in California's vineyards are well controlled by a yeast, Metschnikowia fructicola, applied as a spray shortly before harvest.
