Resistance in Vitis and Muscadinia Species to Meloidogyne incognita . M. ANDREW WALKER, Department of Viticulture and Enology, University of California, Davis 95616. HOWARD FERRIS and MELISSA EYRE, Department of Nematology, University of California, Davis 95616. Plant Dis. 78:1055-1058. Accepted for publication 29 July 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-1055.

Rootstocks resistant to root-knot nematodes are needed for wine, table, and raisin grape culture in California's San Joaquin Valley. As a first step in a breeding program, selections of the following species were screened for resistance to the root-knot nematode Meloidogyne incognita: 10 Vitis acerifolia, 2 V. acstivalis, 4 V. berlandieri, 4 V. californica, 7 V. champinii, I V. cinerea, 2 V. labrusca, 2 V. riparia, I V. rufotomentosa, 2 V. rupestris, and 11 Muscadinia rotundifolia. The rootstocks Freedom, Harmony, 1613 Couderc, and 1616 Couderc were used as standard resistant controls, and V. vinifera cvs. Cabernet Sauvignon, French Colombard, and Thompson Seedless were used as susceptible controls. Three replicates of each selection were inoculated with 1,000 second-stage juveniles; after 4 mo, numbers of second-stage juveniles hatching from egg masses and root weights were determined. Resistance was common in M. rotundifolia, but the difficulty in rooting this species from dormant cuttings and cytogenetic differences from Vitis species may limit its use in rootstock breeding. Promising sources of resistance were also found in V. aestivalis, V. champinii, V. cinerea, V. rufotomentosa, and V. rupestris.