1a.Objectives (from AD-416):
Breed, evaluate, and introduce rootstocks that are resistant to root-knot nematodes and adapted to California's growing season.
1b.Approach (from AD-416):
Screen seedlings for nematode resistance, select superior resistant seedlings, advance selections to field testing and further evaluation, and identify parents for the next round of crossings
We screened more than 2000 candidate grape rootstock seedlings for resistance to aggressive root-knot nematodes. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. Selected seedlings are propagated and then planted into the vineyard. We propagated more than 100 elite nematode resistant selections and cultivated them in a vineyard nursery block. We tested the propagation ability of more than 90 selections (already tested once for nematode resistance). Cuttings produced callus, roots, or shoots in combination (or none of these). We evaluated 22 root-knot nematode resistant grafted selections for their effect on scions, with pruning weight and fruit weight collected from 11 grafted rootstock selections. We applied a technique to evaluate nematode resistance on rooted grapevine leaves to evaluate the nematode resistance of a mapping population that segregates for nematode resistance.