Grape cultivation in California

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. 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. 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. 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. (Uncinula necator) is another costly disease here. 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. 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. See and for a treatment see . s are common in California. is another common trunk dieback here, caused by . 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. E. lata populations in California are shared between three hosts, this one, apricot and willow (Salix spp.). '''' (the California Dagger Nematode, or just Dagger Nematode) is a common disease here. (Measles, Spanish Measles, Black Measles) is a basidiomycete disease caused by several species of the Fomitiporia. (GPGV) was imported in infected 'Touriga National' in 1981 and maintained at UCD, but no epidemic has ever been documented from that contamination. == 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. There is ongoing concern that it will invade again. 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. 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. The rapid shoot growth phase is March to May in the San Joaquin Valley and February to May in the Coachella Valley. See . During postharvest in the SJV, table grape growers should monitor for (Parthenolecanium corni). 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. 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. See also . Thrips are a minor concern in wine and raisin but are significant pests in table varieties. 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. '''' mealybugs are common pests in California's vineyards. 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, Parlier == Breeding of grape ==

This state has the largest breeding program for table grape in the country. 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. was a very popular rootstock here until the 1980s for its protection against grape phylloxera. Since the collapse of AxR#1's phylloxera resistance it has been replaced by a wide diversity of rootstocks. See also . Fuller et al., 2014 finds (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. Riaz et al., 2011 finds 2 major PM resistance loci on chromosome 18 in many of California's grape strains, and . Ramming et al., 2011 find that in the San Joaquin Valley's table/E. necator and raisin/E. necator pathosystems almost all resistance is explained by Ren4. Fuller et al. 2014 also find that widespread adoption of such varieties would save growers as much as $48 million/year in California's table, raisin and Central Coast Chardonnay vineyards alone. Table and raisin production are associated with higher temperature areas of the state. The is located in Parlier. SJVASC produces varieties of table and raisin, including the Thomcord. Many of the state's table and raisin varieties have been produced using embryo rescue. UCD ceased releasing wine varieties in the 1980s. Intensive selective breeding has been ongoing in California since the 1950s for seedlessness in raisin and table. Aradhya et al., 2003 finds that California's accessions of germplasm originates from a single original gene pool. Riaz et al., 2009 introgress PD resistance from into some of the state's susceptible varieties, and provide SSR markers for them. Bowers et al., 1999 develops some of the foundational microsatellite markers for breeding of California Pinot noirs and Cabernet Sauvignons. This et al., 2004 produces a set of standard references for molecular breeding of varieties used here. 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. Petite Sirah is a popular variety in this state. Table and raisin varieties used here come from a very narrow base. == Genetic engineering of grape ==

Up to around 2004 there was little understanding of what non-Vitis genes might provide immunity in grape, and would make good transgenes. at UCD) employed in a large number of transformations at several labs at UCD, at UCD and Los Alamos, (See .) , 1972 == Treatments in grape ==

Zakowski & Mace 2022 finds heavy use of fungicides for cosmetic reasons in the state's table grape industry. Pruning produces wounds which may admit pathogens into the trunk of the vine. See and . The has been very successful since the early 2000s in monitoring and reducing the deadly disease and vector combination of PD and GWSS. and for farmer funded voluntary management programs in general. See and . Prior to the 2000s there were no selective insecticides available for the most important pests of table grape. was a vital chemical for this crop until 2019 especially for the Vine Mealybug. See . Cover crops are used to produce several different kinds of pest and weed control. UC IPM recommends considering the impact of a pesticide application on natural enemies and honey bees before applying to table vineyards. Crab shell chitosan reduces postharvest Gray Mold in table grape in Fresno county. 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. == Research in grape ==

Table grape growers are charged an assessment statewide for research and treatment for PD and GWSS. See , and . California's oenological research is highly respected around the world. == References ==