Ground Cover Supplement : GC Supplement - Cereal foliar fungal diseases
8 Predicting disease DISEASE TOOLS TO LIFT PROFITS new research based on the highly successful daFWa blackspot field pea model will help guide spraying decisions for the costly yellow spot pathogen By Janet Paterson NEW TOOLS UNDER development for yellow spot and stripe rust management will make it easier for growers to make profitable choices when it comes to fungicide applications. They are among a suite of fungal disease-management tools being tackled in a national GRDC project led by the Department of Agriculture and Food, Western Australia (DAFWA) in collaboration with Marcroft Grains Pathology, the New South Wales Department of Primary Industries, the Queensland Department of Agriculture, Fisheries and Forestry, the South Australian Research and Development Institute and the Victorian Department of Environment and Primary Industries. Along with tools related to stripe rust and yellow spot of wheat, the project will also deliver decision-support tools for the management of wheat streak mosaic virus, beet western yellows virus of pulses and oilseeds, blackspot in field peas, ascochyta blight in lentils, powdery mildew of mungbeans, blackleg and sclerotinia of canola and Fusarium head blight in sorghum and wheat. Project leader Dr Moin Salam says the tools will build on the highly successful blackleg (canola) and blackspot (field peas) fungal disease- management tools developed by DAFWA with GRDC funding. "These tools are now used across Australia to guide safe sowing of field peas and effective management of blackleg in canola," Dr Salam says. "We are now in discussion with an international chemical company to convert the blackleg tool into a spray-decision app for smartphones and tablets." The yellow spot and stripe rust tools will integrate the latest information about how the diseases interact with seasonal conditions, variety disease rankings, yield potential and chemical costs. "We will use the blackspot and blackleg models as the basis for the new tools but tailor each with specific epidemic, climatic and agronomic information about yellow spot and stripe rust." The tools will account for the pre- season factors that influence the likelihood and level of disease, along with the seasonal conditions that promote infection and spread of the diseases in-crop. Management recommendations for each disease will be tempered by fungicide costs and anticipated crop value. The tools will be applicable to all of the GRDC cropping regions. "The overall aim of the tools is to highlight the profitability of fungicide decisions and reduce the rate at which fungicide resistance develops by avoiding unnecessary and unprofitable fungicide applications," Dr Salam says. Previous DAFWA research has shown yellow spot and Septoria nodorum blotch (SNB) collectively cause about 11 per cent yield loss across WA. But the profitability of spraying to recover some of this yield loss varies with rainfall and yield potential. "With the current cost of fungicides being relatively low, an application of fungicide to control yellow spot and SNB is often profitable, but many individual trials show no economic return on chemical inputs for these diseases," Dr Salam says. "What we want to do with these tools is to reduce the 'grey area' surrounding fungicide applications, yield response and economic return so that growers can make more informed and profitable choices surrounding disease management." The biology of each of the diseases will be captured in the tools so that the intricacies of each pathogen's spore production and spread can be modelled accurately according to past and present seasonal conditions and cultural practices. "We know from the blackleg and blackspot models that identifying the timing and nature of spore production can vastly reduce the impact of these diseases on early seedling development," Dr Salam explains. Many field pea growers across southern Australia now rely on the blackspot model, delivered online and via an SMS service, to guide sowing decisions. "The blackspot model has lifted the profitability of WA field pea growers by an estimated $1.2 million," Dr Salam says. "We want to extend the success of the blackspot and blackleg models to other diseases to lift the profitability and sustainability of fungal disease management across Australia." □ grdc research code daW00228 more information: Dr Moin Salam, DAFWA, 08 9368 3333, email@example.com PHOTOS: DAFWA (Right) 'Timing is everything': a yellow spot fungal fruiting body erupts sending a mass of spores into the air. (Below) The yellow spot pathogen harbours on stubble over summer with spores released from the black fruiting bodies following rain.
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