Breeding of Disease Resistant Grape Varieties in New York
Nursery Selection Under "No-Spray" Conditions: Since 1996, we have been selecting seedlings in a "no-spray" nursery. Seeds are germinated in the greenhouse and then the young plants are transplanted into the nursery. The nursery is trickle irrigated and weeds are controlled, but neither fungicide nor insecticide sprays are used. The primary leaf disease problems are powdery mildew (Uncinula necator) and downy mildew (Plasmopara viticola). The severity of the natural disease infection varies somewhat with the seasonal weather conditions and the degree of resistance in the seedling population being studied. In the fall, it is not uncommon to find entire susceptible populations that have been severely defoliated by disease. In September and October, we select the most resistant individuals to save for permanant plantings, and discard the susceptible individuals.
Vineyard Selection Under "No-Spray" Conditions: Vines that have been preselected in the "no-spray" nursery are planted the next year in the seedling block of our "no-spray" vineyard. Normal vineyard cultural practices are used in this vineyard, however no fungicide or insecticide applications are made. The cultivars 'Concord', 'Steuben' and 'Chancellor' are used as standards and yearly evaluations are made for trunk injury, vine vigor, crop load, and disease ratings of leaves and fruit. Over the course of several years, individuals that show an unacceptable level of disease susceptibility, poor fruit quality, or unsuitable vineyard characteristics, or imperfect flowers are discarded. Selections that have good disease resistance and good vineyard qualities are propagated to our second test block for further evaluation and wine testing.
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