CHARACTERIZATION OF PRATYLENCHUS-PENETRANS FROM 10 GEOGRAPHICALLY ISOLATED POPULATIONS BASED ON THEIR REACTION ON POTATO

Single female cultures of Pratylenchus penetrans were established from soil and root samples collected from 10 geographically isolated locat ions in North America. The resultant isolates were used to evaluate ne matode egression from and multiplication on roots of potato clones to distinguish intraspecific differences among isolates. The 10 nematode isolates were statistically separated into four groups based on percen tage of nematodes that egressed from the P. penetrans-resistant potato clone L118-2. The Cornell (CR), Wisconsin (WI), Long Island (LI), and Adirondack (AD) isolates, selected as representative isolates of each of the four groups, exhibited 53%, 39%, 25%, and 10% egression from L 118-2, respectively. Reproduction of these four isolates was measured on three potato cultivars (Russet Burbank, Butte, and Hudson) and two breeding lines (NY85 and L118-2). The LI and AD isolates reproduced we ll on all five potato clones. The CR isolate reproduced well on Russet Burbank and NY85 but significantly less on Butte, Hudson, anti L118-2 . Reproduction of the WI isolate was less than the LI and AD isolates but was less than the CR isolate on all potato clones tested except Ru sset Burbank. Reproduction of the WI isolate on Russet Burbank was les s than the other three isolates. Based on these results, four distinct intraspecific variants of P. penetrans are proposed: Cornell, Wiscons in, Long Island, and Adirondack.