Soybean Bud Blight: Seed Transmission of the Causal Virus

Abstract

Bud blight of soybean, as a symptom, can be induced by at least four viruses. Tobacco ringspot virus (TRSV) is the most common incitant, followed by tomato ringspot virus, tobacco streak virus and the necrotic strain of soybean mosaic virus. The disease, first reported in Indiana, USA in 1941 by Samson who established TRSV as the causal virus, has been reported since in Canada, in the eastern region of the USSR and in Himachel Pradesh, India. Seed transmission of TRSV in reservoir hosts may play a key role in the epidemiology of bud blight. Seed transmission occurs in many virus-host combinations. Not all viruses, however, are seed transmitted; about 100 of the more than 400 viruses described are transmitted in this way. TRSV is efficiently transmitted by soybean seed; rates of transmission are often in excess of 90%, especially in seed from plants infected at an early age or in seeds from plants arising from infected seeds.