Mahdi Davari - Department of Plant Protection, Faculty of Agriculture, University of Mohaghegh Ardabili, Ardabil, Iran.
Naser Safaie - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Mostafa Darvishnia - Department of Plant Protection, Faculty of Agriculture, University of Lorestan, Khoram Abad, Iran.
Rahim Didar Taleshmikaeel - Department of Plant Production, Moghan College of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.

The severe epidemics of Fusarium head blight (FHB) as a devastating disease of cereal crops has occurred on wheat in North and Northwest Iran in recent years. The in vitro production of Deoxynivalenol (DON) was qualitatively evaluated in ۴۱ Fusarium isolates collected from wheat heads associated with the scab disease, in Moghan area/Northwest Iran. Infected wheat heads were collected during ۲۰۰۴-۲۰۰۷. The isolation of causal agents was carried out using standard methods. According to morphological characteristics and using valid descriptions, all isolates belonged to Fusarium graminearum species complex and F. culmorum of which the former was dominant. In order to evaluate the potential of DON production in isolates, this mycotoxin was extracted and qualitatively examined by TLC method. The quantification of DON was achieved using HPLC method. TLC results indicated that ۵۴.۵% of studied isolates produced DON but there was no significant relationship between this property and cultivars or sub-regions or years. Also based on HPLC analysis, maximum content of DON was detected in F. graminearum isolated from cv. Izen green from Moghan Agro-industry company fields in ۲۰۰۴ at the rate of ۵۸۲۷.۱۱ µgkg-۱. The results of present study show that DON mycotoxin is produced at various contents by F. graminearum isolates on different cultivars and from different origins/ years. Since DON plays a role in pathogenesis and is of paramount importance in contamination of wheat grains, these results give a better insight into the significance of this disease in Northwest Iran.

Chemotype, DON, F. graminearum sensu lato, Fusarium head blight, Northwest Iran