Poster Presentation Science Protecting Plant Health 2017

Neocosmospora root rot and Tobacco Streak Virus as a disease complex of peanut in central Queensland, Australia (#236)

Kylie M Wenham 1 , Murray Sharman 2 , Victor J Galea 1 , Malcolm Ryley 3
  1. School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD, Australia
  2. Department of Agriculture and Fisheries, Brisbane, QLD, Australia
  3. University of Southern Queensland, Toowoomba, QLD, Australia

The incidence of a virus and fungal pathogen coexisting within the roots of the same plant is an uncommon occurrence. Tobacco streak virus (TSV) has been known to cause significant crop losses of sunflower (Helianthus annuus) and mungbean (Vigna radiata) and has been recorded in peanut (Arachis hypogaea) plants in the Emerald region of central Queensland, Australia. Neocosmospora root rot (Neocosmospora vasinfecta var. africana) is an emerging pathogen that has also caused extensive damage to peanut crops in this region during intermittent outbreaks. In 2016, peanut plants in a commercial crop near Emerald exhibited wilting of the main stem, leaf chlorosis and root decay with orange-reddish perithecia of N. vasinfecta var. africana developed on necrotic areas of the main taproot and lateral root system. These symptoms and signs were consistent with infection by Neocosmospora root rot of peanut. Other plants in the crop displayed typical foliar symptoms of virus infection such as stunted growth with chlorotic or necrotic leaves and shortened internodes. N. vasinfecta var. africana was isolated from the roots of 95% of plants with symptoms of Neocosmospora root rot and ELISA testing detected TSV in 80% of these roots. The virus was not detected in the leaves of these plants infected with both pathogens. Although TSV was detected in the leaves and the roots of the plants exhibiting typical foliage symptoms of virus infection, N. vasinfecta var. africana was not isolated from any of their roots. These results suggest an unexpected relationship between TSV and Neocosmospora root rot that has contributed to outbreaks of a root disease complex of peanut crops in central Queensland.