Reaction of Grape Rootstocks to Ring Nematode Mesocriconema xenoplax

Abstract

The reaction of grape rootstocks to the ring nematode Mesocriconema xenoplax was studied in glasshouse experiments and in a vineyard trial. Growth of one Oregon population of M. xenoplax differed among 20 rootstock and self-rooted cultivars grown in the glasshouse for eight months. The reproductive factor, Rf (final nematode density divided by initial nematode density), was ≤0.5 for 420A Mgt rootstock and ≤2.4 for 101-14 Mgt and 110R rootstocks; Rf values ≤1 indicate high nematode resistance. Other rootstocks had Rf values between 6.9 and 52.5. Root dry weights of all varieties except 420A Mgt were reduced by M. xenoplax. In another glasshouse experiment, 420A Mgt and 101-14 Mgt were found to be resistant to one Washington State and four Oregon populations of M. xenoplax, although both were moderately susceptible to a California population. A root-stock trial was planted in 1997 in a vineyard infested with M. xenoplax. After six and seven years, population densities of M. xenoplax were lowest in vines on 420A Mgt (≤0.08 g⁻¹ soil) and 101-14 Mgt (≤0.24 g⁻¹ soil) rootstocks. Population densities on other rootstocks ranged from 1.25 to 4.57 g⁻¹ soil. 420A Mgt produced good vine vigor and yield and showed the highest degree of M. xenoplax resistance. Rootstock 101-14 Mgt, which is widely used in Oregon, was also resistant but produced only average vigor and yield. Other common Oregon rootstocks, Riparia Gloire, 3309C, and self-rooted Pinot noir, were highly susceptible to M. xenoplax and were among the least vigorous vines.