Race composition and distribution of broomrape (Orobanche cumana Wallr.) in Bulgaria during 2007-2011

Abstract

In order to determine the race composition and distribution of broomrape in Bulgaria during the period 2007-2011, samples (seeds) of the parasite were collected in 116 different locations from the main sunflower production regions. The collected seeds were used to infect differential sets of genotypes by a standard methodology. According to the results obtained from this investigation, the broomrape population in Bulgaria includes 4 races: E, F, G and H. Races E and G were most widely distributed. During the years of investigation race E gradually decreased its percentage in the population but was still predominant in the region of north-east Bulgaria while becoming almost equal with race G in the region of central north Bulgaria. In south-east Bulgaria, the population included only race G, which will probably increase its percentage in other regions as well in the upcoming years. Race F was of sporadic occurrence. It was isolated in single years, its distribution was limited and there is no danger of its mass occurrence. The population identified as race H was isolated only in 2007. This population may be considered a primary source of infection that will be expanding from now on; for the time being, however, it is localized on a very small area.