The first report of Fusarium culmorum and Fusarium subglutinans in onion from West and East Azarbaijan provinces

Various Fusarium species are pathogenic groups that cause economic loss (quantitatively and qualitatively) in Allium cepa L., Fusarium species including F. culmorum and F. subglutinans are of great importance in all onion growing areas. Fusarium infection usually starts from the farm and continue throughout the storage and marketing. Fusarium and basal rots of onion are important around the world. In recent years, they had a large spread in the major onion growing areas in West and East Azarbaijan provinces, and now are the most important disease of onions in Iran. Therefore, in order to identify and study this disease in major areas of cultivation, samples were taken from several fields in East Azarbaijan (Ilkhchi, Azarshahr, Ajabshir, Bonab, Malekan, Marand, Maraghe) and West Azarbaijan (Miandoab, Khoy, Salmas) in summer 2012. After isolation and purification, 140 isolates were obtained. Eighty isolates were selected for pathogenicity test on onion bulbs of which 42 were pathogenic. Among the 42 studied isolates, they categorized as extremely (14.28%), highly (26.19%), moderately (40.48%) and weakly (19.05%) virulent. Based on morphological characteristics and molecular identification using species-specific primers, eight species were confirmed. Out of the 42 isolates studied, F. subglutinans, with a frequency of 2.38% and 43% disease severity and F. culmorum, with a frequency of 7.14% and 50% disease severity are reported for the first time on onion in these areas.