Effective management of viruses in pulse crops in south eastern Australia should include management of weeds

Abstract

This study addressed the role of weeds in the epidemiology of the six most important pulse viruses in the production areas of south eastern Australia- Alfalfa mosaic virus-Bean yellow mosaic virus-cucumber mosaic virus-pea seedborne mosaic virus-bean leafroll virus-beet western yellows virus-pulse viruses-legume viruses-weeds. We found that the weed host range of these viruses was greater than previously reported and that not only were weeds a potential source of virus during the cropping season, but many persisted over hot, dry summers providing a “green bridge” for the viruses and their aphid vectors between cropping seasons. Weed surveys were conducted for the six pulse viruses in and around pulse crops during the 2000–2001 growing seasons. Virus was detected in 55 of 180 weed samples (selected as representative of 1416 samples), which included 15 species in 12 genera of seven families, including six allegedly new host-virus records. A weed survey was conducted between pulse growing seasons, over the summer of 2002 to determine the survival of weed hosts. It was found that even under severe drought conditions most weed species survived in a range of locations, providing a potential reservoir for viruses and allowing aphid vectors to over-summer on green hosts. Inoculation of 36 weed species common to the area resulted in additional potential weed hosts. As a result, weed control would seem to be an important element in controlling viruses in pulse crops in south eastern Australia.