In this section:
Clover red leaf disease
Development and use of diagnostic tools for subterranean clover red leaf disease
Overview
In recent years sub clover seed producers and sub clover pasture growers have reported reddening in sub clover plants (Figure 1) and reduction in dry matter production and seed yields. Surveys conducted in the southeast of South Australia and western Victoria in the spring of 2008 and 2009 showed viruses were often the cause of the leaf reddening. The principal viruses to affect sub clover were Bean leaf roll virus (BLRV), Cucumber mosaic virus (CMV) and Alfalfa mosaic virus (AMV). These three viruses have a wide range of legume hosts and are transmitted by aphids. CMV and AMV are also seed transmitted at low rates.
Molecular Diagnostics
The red-leaf symptoms can be caused by a range of viruses and can easily be confused with nutritional deficiency symptoms or physiological reddening caused by cold temperature and/or water logging. For these reasons it is worth having the presence of virus confirmed by molecular testing which can be conducted by Waite Diagnostics
Disease Management
An integrated approach should be taken to reduce the risk of virus infection in sub clover pastures. The major things to do are: confirm the presence of viruses; decrease the reservoirs of viruses and aphids over summer; reduce the spread of aphids and viruses by locating sub clover seed crops away from lucerne fields, delayed sowing and the strategic use of insecticides.
More Details
For more details see “control of red leaf disease in sub clover seed crops” (PDF 185KB).
Figure 1: Red leaf disease in clover
