Virulence of sunflower broomrape (Orobanche cumana Wallr.) in some regions of Northern Caucasus

Abstract

After a long period (about 30 years) without broomrape problems in sunflower fields, intensive infestations were observed in some parts districts of Northern Caucasus. Virulence of the pathogen populations from some regions of Northern Caucasus was compared with those of race F from Spain and a mixture of races F, G, H from the European part of Turkey. It was shown that the broomrape populations from Northern Caucasus have heterogeneous structure. The populations Svetlogradskaya, collected in 2005, and Morozovskaya, collected in 2006, were most virulent. The first has the virulence comparable to one from Turkey and it is a mixture of nonvirulent and virulent races for the studied sunflower genotypes. Race F predominates in the mixture and has a there is an admixture (although insignificant) of more virulent individuals. The population Privolnenskaya from 2003 collection, is a mixture of different races also, but it is less virulent, containing race E and some insignificant admixture of more virulent individuals (most likely race F).