spp. Associated With Root Rot of Pulse Crops and Their Cross-Pathogenicity to Cereal Crops in Montana.

Root rot caused by species is a major problem in the pulse growing regions of Montana. isolates ( = 112) were obtained from seeds and roots of chickpea, dry pea, and lentil. Isolates were identified by comparing the sequences of the internal transcribed spacer region and the translation elongation factor 1-α in -ID database. was the most abundant species (28%), followed by (21%), (13%), (8%), (6%), (6%), (6%), (4%), (2%), (2%), and (0.9%). The aggressiveness of a subset of 50 isolates that represent various sources of isolation was tested on three pulse crops and two cereal crops. Nonparametric analysis of variance conducted on ranks of disease severity indicated that and isolates were highly aggressive on pea and chickpea. In lentil, and were highly aggressive. In barley, , , , and were highly aggressive. In wheat, , , and were highly aggressive. Two isolates were highly aggressive across all the crops tested and found to be cross-pathogenic. One isolate of and an isolate of . obtained from chickpea and lentil seed were highly aggressive on barley and wheat. The results indicate that multiple spp. from seeds and roots can cause root rot on both pulse and cereal crops. Rotating these crops may still lead to an increase in inoculum levels, making crop rotation limited in efficacy as a disease management strategy.