شناسايي، پراكنش و علايم شناسي عوامل بيماري ساق سياه كلزا (Leptosphaeria maculans و Leptosphaeria biglobosa) در استان‌هاي مازندران و گلستان و تعيين حساسيت سه رقم تجاري كلزا

IDENTIFICATION, DISTRIBUTION AND SYMPTOMOLOGY OF THE CAUSAL AGENTS OF RAPESEED BLACKLEG (Leptosphaeria maculans AND Leptosphaeria biglobosa) IN MAZANDARAN AND GOLESTAN PROVINCES AND DETERMINATION OF THREE COMMON RAPESEED CULTIVARS SUSCEPTIBILITY REACTION

During 2007-2008, Leptosphaeria maculans and L. biglobosa the causal agents of rapeseed blackleg were identified based on leaf and stem symptoms and morphological characteristics (teleomorph and anamorph) in Mazandaran and Golestan provinces. Among 49 Leptosphaeria isolates, 43 isolates were obtained from rapeseed (on leaves, stem and debris) in six regions and six isolates from wild mustard (Sinapis arvensis L.) on debris in two regions. Disease symptoms were observed on cotyledons, leaves and taproot. Pathogenicity group (PG) of seven isolates from both of hosts was determinated based on phenotypic interaction (PI) of isolates on three differential cultivars of Westar, Quinta and Glacier. Four isolates were belonged to PG1 (L. biglobosa), one isolate PG2 (L. maculans) and two isolates PGT (L. maculans). Mustard isolate was belonged to PG1. This is the first report of the occurance Leptosphaeria maculans PG-T on rapeseed and L. biglobosa on wild mustard in Iran. Also, Suscebtibility of okapi, Zarfam and Hyola401 cultivars were investigated to Leptosphaeria isolates. All of three cultivars were highly suscebtible to PGT (Do4-12 isolate).