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Stemphylium grey leaf spot disease of lupins in Western Australia
The aim of this study is to assess the risk posed by Stemphylium grey leaf spot disease to lupin crop of WA and relationship of that with environmental variables. It would ultimately lead to the development of a disease forecast model. The disease has been among the major constraints to lupin production in WA in the past. During the 1970’s the disease caused heavy yield losses. Wild accessions of Lupinus angustifolius were found resistant to the disease in the USA. This provided a source of resistance - later incorporated into WA varieties. Though the disease remained continuously associated with the crop, over the last 20 years it remained inconspicuous in WA lupins due to the continued breeding of resistant cultivars. Recently however, the disease has been again observed at damaging levels and screening of breeding lines indicates that a proportion of the existing breeding material no longer contains resistance to this disease. There is a risk that it may re-emerge as a devastating disease due to climate change, which could favour the survival and spread of the pathogen making the crop more vulnerable to attack on a large scale.
There has been no comprehensive research on Stemphylium grey spot in WA i.e. which fungal species are responsible for the disease, what is their physiological behaviour and host range, and what type of environment favours disease outbreaks etc. This information is particularly important for the breeders to make decisions about the breeding activities. Study of the risk associated with this disease would effect the consideration to be given to this disease. With other diseases of lupins such as anthracnose and brown spot etc. already present in the field, there is a need of more focused approach against this disease rather than trying to conserve the resistant genes for this disease that may reduce the variability in germplasm and hinder the activities to make the crop resistant against other diseases. Disease forecast model would be helpful in implementing integrated disease management strategies.