The USDA grape rootstock improvement program, based at the Grape Genetics Research Unit, is breeding grape rootstocks resistant to aggressive root-knot nematodes. We define aggressive root-knot nematodes as those which feed on and damage the rootstocks Freedom and Harmony. In 2009 we screened 5126 candidate grape rootstock seedlings (representing 69 different populations) 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 screened an additional 420 seedlings for nematode resistance genetics studies. We tested the propagation ability of 190 selections (already tested once for nematode resistance) and of these retested 80 selections to confirm nematode resistance in replicated trials. We planted eleven selections, grafted to Syrah, into a new rootstock trial at the University of California Kearney Ag Center and identified eleven more selections to be grafted to Syrah for a rootstock trial to be planted in 2010. We pollinated 317 clusters of crosses in 55 unique combinations specifically aimed at the breeding of improved rootstocks with resistance to aggressive root-knot nematodes. Virus testing is complete for our most elite selections and several of these are candidates for possible variety release.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF2009-10-16 08:28:502017-10-16 08:29:38Project title: Breeding rootstocks resistant to aggressive root-knot nematodes