Increase in virulence of sunflower broomrape in Serbia

Abstract

Sunflower broomrape (Orobanche cumana) is a parasitic plant that can have significant negative impact on yield. Change in virulence of parasite is a potential threat for sunflower production, as resistant hybrids growing is an extensively used control measure. Increase in broomrape virulence has been reported frequently in a number of countries with sunflower as major crop and with a long presence of parasite. In Serbia, virulence of broomrape was described as race E. In our research, broomrape seeds were collected from infested fields and virulence was determined using sunflower lines differing in resistance. Experiments were conducted in greenhouse, by sowing sunflower seed in pots with substrate containing conditioned broomrape seeds. Sunflower roots were evaluated for parasite presence after six weeks. Results of greenhouse trial indicated presence of race F at one site, as broomrape was present on roots of lines LC 1003 and NR5 that are resistant to race E and susceptible to broomrape populations with virulence higher than E. Parasite was absent in line P96, resistant to race F. Increase in virulence was further confirmed with susceptible reaction of selected hybrids resistant to race E. To our knowledge, this is the first report on occurrence of broomrape race F in Serbia, on small infestation spot.