The effects of P vulnus on the apple rootstock EMLA 26 and the pear rootstock OHF-333 were evaluated in vitro and under greenhouse conditions. In vitro, P vulnus caused extensive damage to both rootstocks in the absence of microorganisms. Earliest penetration was recorded at 2 days for both hosts. Nematodes appeared to converge to one or two points of entry. During the course of 28 days, cortical parenchyma became extensively colonized and developed lesions and cavities. Pratylenchus vulnus was randomly oriented within the cortex and did not invade meristems or conductive tissues. Visible lesions appeared at 7 days and expanded rapidly. In greenhouse experiments, shoot length, and fresh top and root weights in 5-month-old apple and pear were significantly lower in P. vulnus treatments than in uninoculated controls. Plant growth of pear did not differ between treatments receiving 50 and 500 nematodes/plant. The EMLA 26 rootstock was more susceptible to P. vulnus than the OHF-333 pear
