New canola blackleg spore shower forecast available
DAFWA’s latest blackleg spore shower forecast is now available.
The DAFWA blackleg sporacle model predicts the onset of blackleg ascospore release from canola stubble for 25 canola growing districts of Western Australia using the latest weather data from the nearest weather stations to these locations.
Due to lack of sufficient rain the fruiting body maturation process has halted or slowed down in many canola growing areas of the state.
Based upon the latest weather data, the model is currently predicting that the fungal fruiting bodies are now mature in Jerramungup and Salmon Gums which means blackleg spores are now releasing in these areas. Fruiting bodies are very close to maturation in Esperance Downs, Scaddan, Munglinup and Mount Barker districts.
Canola pathologist Ravjit Khangura (DAFWA) encourages farmers in these areas to plant canola at least 500m away from last year’s canola residues and use in-furrow and seed dressing fungicides in high disease pressure situations.
Applying a foliar fungicide is beneficial in the following situations;
- Where growers have missed the opportunity of applying an up-front fungicide application.
- When continuous wet conditions experienced during susceptible canola growth (up to six leaf stage) increase the number of successful infection events.
The model also shows that depending upon the rainfall events in the coming weeks the fungal fruiting bodies may mature earlier in Lake King, Lake Grace, Katanning, Narrogin, Darkan and Williams shires.
In some central and eastern shires (Northam, York, Tammin and Merredin) the spore maturity hasn’t progressed much; therefore the risk of spore showers coinciding with canola seedling emergence in these areas remains unchanged at this stage.
In a majority of northern areas (Northampton, Eradu, Mingenew and Mullewa) the spore maturation process has not yet commenced and consequently the risk of spores falling at the susceptible canola seedling stage is currently very low in these areas.
Visit the Canola blackleg spore maturity forecast for Western Australia page to find out the forecast for other shires. The blackleg spore shower risk will change each week as the season progresses depending upon the weather conditions in the coming weeks, therefore, growers are urged to check the weekly updates.
The overall risk of blackleg infection on a property will be determined by factors such as resistance level of the canola variety, paddock rotation, years of using the same resistance group, fungicide usage, distance from previous year’s canola residues and stubble reduction.
For further details on blackleg management and current blackleg ratings refer to Grains Research and Development's (GRDC) Blackleg Management Guide (2017 autumn variety ratings).
For more information contact Ravjit Khangura, Research Officer, South Perth on +61 (0)8 9368 3374.