The Table Grape Collection
· The grapes came from the collection at Prusch Park, San Jose (Todd Kennedy’s collection which he collected and rescued from germplasm that was being deaccessioned from other fruit repositories).
· These grapes, called both American table grapes and Eastern Hybrids, are seeded table grapes and grown for dessert, not for wine making.
· Nearly all are hybrids and crosses between Vitis labrusca, or Vitis aestivalis and V. vinifera.
· Grapes are propagated by hardwood cuttings taken in January during the dormant period and are their own roots.
· They are grown the first year to get them established and training starts the second dormant period after their root systems have become established
· They are trained to have only one trunk and are headed back at the height of the training wires and the sprouts from this cut are then selected for the fruiting canes.
· Only 4 canes are selected per plant and they are headed once they reach a certain point.
· They are usually cane pruned rather than spur pruned like wine grapes and they need a wire support system.
· All sorts of vertebrate pests are a threat to grapes, so solar-powered electric fencing is used to discourage these animals during the ripening season.
· Problems: gophers and voles, powdery mildew, oak root fungus, eutypa die back(“dead arm” disease, and phylloxera (root louse)
The phylloxera story:
Phylloxera is an aphid-like insect, called a root louse. It is a native insect from the Eastern to Southeastern part of the United States. It took its time getting to California and was introduced here in 1850. Prior to that event California was the only place in America that could grow Vitis vinifera, the European wine grape, and it was well grown at the California missions. Bartram, Jefferson, Washington and other early American agriculturists tried European grapes and were not successful because of the phylloxera and also the poor climate. This insect feeds only on Vitis vinifera and its hybrids. The insect was introduced to Europe in 1863 and by 1890 it has destroyed about two thirds of the wine grapes and the industry in Europe. Looking to other sources for the making of alcoholic beverages this of course had its effects on promoting the finest apple and pear cider industry in Northern France and in England.
At the turn of the century phylloxera had become such a pest in California that it destroyed the early wine industry of the state and of course close to home, Mr. Bourn’s vines in St. Helena. There were quite a bit of wine grapes planted in the Woodside area and they were wiped out also. It wasn’t until viticulturists learned that they could use the American native grapes, Vitis labrusca (fox grape) and some of their hybrids as grafted rootstock that a control became possible both here in America and in Europe. It was the hybrid rootstocks developed by viticulturists in France, by crossing Vitis vinifera with the resistant American species grapes that worked as the best rootstocks and saved the Californian wine industry.
The tiny adult insect lives above ground and also down in the soil where it feeds on roots and stunts the plant as a result. Deep down it cannot be reached even with the most powerful modern fumigants. Grape roots can be found 6’ down in the soil. Most of the phylloxera are wingless females and they are very small and hard to see.
The story continues today. U. C. Davis blundered terribly by sending out rootstock that was not really resistant to phylloxera and marketing it to a large number of wineries in Napa and Sonoma in the 1980’s. Huge amounts of land were planted with it. In the 1990’s the phylloxera became a real problem again in California and Europe on vines that had been grown on this untested rootstock. This story really shows how germplasm preservation is so important. If the native American grapes had no longer existed, those genes would not have been around to use in the breeding programs that created the new American phylloxera-resistant rootstocks.
· Watered by drip irrigation with emitters controlled by an automatic irrigation controller
· Weeds are controlled by using weed barrier cloth and mowing several times during the spring and early summer.
Head of Horticulture
Internship Program Coordinator
86 Cañada Road