Pests and Diseases

UK: Early warning for more active blight risk

Blighted leavesPotato growers and agronomists can be better prepared to cope with more aggressive blight strains this season, with the new Syngenta website BlightCast warnings, tailored to focus on infections now typically occurring earlier in the season at cooler temperatures. The new forecasting model, developed by Syngenta agromet specialists, uniquely predicts conditions conducive to blight strains that develop more rapidly at lower temperatures. This reflects the changing dynamics of today’s blight populations more effectively, believes Syngenta Technical Manager, Douglas Dyas. “In recent seasons the first signs of foliar blight could be found on volunteers and unprotected crops even before any conventional Smith Periods had been recorded,” he reported. “Clearly blight was active earlier and at lower temperatures that we previously considered.”

The ‘New Criteria’ in the BlightCast forecast pinpoints when local temperatures are set to hit over 8°C and more than 11 hours at 90% humidity over two consecutive days to trigger a Blight Risk Period, or a Near Miss where conditions occur for a shorter duration.  “With BlightCast growers and agronomists can now have up to five days advance warning of these conditions, which means they can be more proactive in their spray programmes and product choice,” advised Douglas.

“It reinforces the importance of starting the blight programme early, and utilising the highly effective blight fungicide, Revus, early in the programme to protect new foliar growth,” he advocated. The new cooler temperature activity is now being evaluated by leading independent blight researchers, as the conditions where they believe today’s blight strains may already be active. The free BlightCast service also provides exclusive spray-window forecasts. These detail potential application opportunities according to weather conditions, which could prove crucial to ensure protective fungicides can be successfully applied before blight risk hits.

“With potato growers often operating large acreages across a wide geographic area, the spray-window forecast could prove invaluable in helping to prioritise application scheduling,” according to Douglas.

The high risk of early blight infection has been widely reported this season. The exceptionally mild over winter conditions, and now the delayed start to planting, could mean crops emerging to greater infection pressure of spores from infected volunteers and dumps. “Having a more proactive tool that will flag up potential problems early will ensure all growers are better prepared. It could help to minimise early outbreaks, and reduce overall build-up of blight infection risk across all crops.”

BlightCast is now available for growers to register in the dedicated potato agronomy area of the Syngenta website:

Editor & Publisher: Lukie Pieterse

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