Despite the dry conditions, growers are being warned to check barley crops for disease following reports of Spot Form Net Blotch (SFNB) in Queensland and northern New South Wales this winter.
Prolonged dry weather has historically reduced disease pressure on crops, but pathologists have been fielding a number of calls regarding SFNB in barley crops in Central Queensland and the Bundaberg and western downs areas. Reports of SFNB have also come in from the Croppa Creek region of northern NSW.
Department of Agriculture and Fisheries (DAF) pathologist Lisle Snyman said the disease prevalence was unexpected given dry conditions but being moisture-stressed may have made some crops more vulnerable this season.
“While we are surprised to see the level and extent of disease given the dry, we also know SFNB tends to prevail in tough conditions where plants are moisture stressed, making them more pre-disposed to infection,” she said.
“While many of the reports coming in are from crops under irrigation, a few relate to dryland paddocks.
Dr Snyman said it was critical growers and agronomists checked crops for disease and evaluated the benefits of spending valuable dollars on fungicide treatments this season.
“Vigilant disease management is the key to reducing the impact of the disease and maximising the yield,” she said.
“However, assessing the yield potential of crops, or determining their potential end use this season, will really govern how and what growers should spend on fungicide treatments.”
Dr Snyman said growers would be advised to consider the withholding periods of fungicide treatments, particularly if crops were intended for stock consumption or forage.
Grains Research and Development Corporation (GRDC) Crop Protection Manager – North, Vicki Green, said long-term-tactical approach to SFNB was important.
“In dry seasons there is generally lower disease pressure. So, when disease is present your decisions about fungicide application costs versus potential economic returns are not always straightforward,” she said.
“In comparison, when there is high disease pressure, usually from wet conditions early in the season, then a robust spray strategy can improve grain quality, yield and returns to the grower.”
Growers are encouraged to consider implementing across-season tactics to reduce the risk of net blotch outbreaks and resistance selection. These include rotating crops or managing stubble to minimise disease carry-over and selecting more disease-resistant barley varieties to reduce potential disease severity.