شناسایی، مقایسه بیماری‌زایی و تعیین پراکنش شبه گونه‌های Bipolaris عامل پوسیدگی ریشه و طوقه گندم در استان کرمانشاه

In order to diagnose form species of Bipolaris involving root and crown rot of wheat plants and determine their distribution, frequency and disease severity, 410 wheat fields (W. Fs.) in different regions of Kermanshah province were sampled at seedling, tillering and heading stages during three crop years (1997– 2000). Also 90 W. Fs. (30 per year) in different regions of the province were chosen randomly to estimate percentage of infected wheat plants. For the isolation of the fungi from tissues of root, subcrown internodes, crown and foot, the tissues were surface sterilized and placed on culture media. The results showed that there were some root and crown rots in the most regions of the province and the percentage of diseased plants was 0-24%, whose average was 3.2%. Forty three isolates belonging to form genus Bipolaris were isolated including form species B. sorokinina, B. cynodontis and B. spicifera. All three form species were pathogenic under greenhouse conditions. Disease severity and frequency of B. sorokinina were more than the others. Disease severity of B. cynodontis and B. spicifera was the same and their differences compared with the control were significant.