Evaluation of Milioncast, a Forecaster for Onion Downy Mildew, with Historical Data
Downy mildew, which is caused by Peronospora destructor (Cook, 1932), is a very common disease of bulb and salad onions. Yield losses of up to 75% in bulb onions have been recorded (Develash and Sugha, 1997). Fungicides to control downy mildew are often applied prophylactically, as frequently as every 10 days. However, such frequent use is very costly to growers, increases environmental risks and pollution, and increases the selection pressure for fungicide resistant isolates within P. destructor populations. Furthermore, the number of active compounds that are allowed has been reduced as a result of changes in fungicide regulations. Thus, forecasters are needed to use fungicides more efficiently and effectively by timing the applications better to when actual disease development occurs.
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