incidence of cereal cyst nematodes (heterodera avenae type b and h. filipjevi) in southwestern iran

a survey of cereal fields of khuzestan province during 2008-2011 revealed that cereal cyst nematodes (ccns) are widely distributed in this region. the ccns were present in 37 and 35% of the 200 samples collected from wheat and barley fields respectively. the species were identified as heterodera avenae type b and h. filipjevi the morphological and morphometric identifications of which were confirmed by rrna-its rflp. population density of ccns ranged from 2 to 103 cysts (mean 18)/100 g of dried soil with an average of 395 (0-3400) j2 and eggs in wheat samples. whilst the number of cysts in barley samples were counted 3-71 cysts (mean 11) /100 g soil, the j2 and eggs averaged 166 (0-900). the lowest and the highest rates of infestation (8 and 83%) were observed in the regions of ahvaz and behbahan respectively. the number of j2 and eggs of ccns in some regions were greater than the damage threshold level considered for ccns and it is likely they could cause economic yield loss in these regions.