Soil-borne mosaic viruses in winter barley: Effects of variety and management

Abstract

In an aerial survey in 1988 of 30,000 ha in the Cotswolds, 13% of the winter barley acreage was affected to some extent by virus. In a three-year experiment on three cultivars on the effect of nitrogen rate and timing on virus incidence and severity, there was an indication that nitrogen in November led to earlier symptom expression, but there was no evidence that nitrogen had any effect on virus concentration within plants. Nitrogen timing had a greater influence on yield of the resistant cultivar Torrent than on susceptible cultivars Igri and Plaisant. Cultivar resistance to virus was investigated. At one site, where the resistance- breaking strain of Barley Yellow Mosaic Virus was present, all cultivars were affected, but in most of the 'resistant' cultivars virus symptoms were less distinct and faded earlier than in the 'susceptible' cultivars. At the other three sites, where trials were harvested, a greater range of cultivars was affected at the two sites with Barley Yellow Mosaic Virus than at the site with Barley Mild Mosaic Virus only. The yield advantage of the resistant cultivars over the susceptible standard Igri was generally in the range 38 - 50%, but up to 72% at one site. There was also a four-year study of the survival of virus and vector in the soil. There was no evidence that a one, two or three year break with winter wheat or with a resistant winter barley cultivar had any effect on virus or vector survival.