CHOOSING A BLIGHT fungicide that quickly becomes rainfast and is resilient to wash off will be key to any control strategy this season, potato growers have been told.

Products with good rainfastness provide more flexibility to fit blight control strategies with irrigation regimes, or can be used in showery weather, said Dow AgroSciences’ Andy Leader.

“Farmers want a blight fungicide that makes the most of the spray days available and so allows them to keep tighter spray intervals.”

He suggests growers use the firm’s mid-season fungicide, Electis (mancozeb), which is rainfast after one hour and performed well in UK trials last year, he said.

In the trials, 25mm of irrigation water was applied six hours after the fungicide treatment. After three days Electis treated plots showed 1% blight infection and after seven days this increased to 7%, he said.

This compared to 3% and 18% infection respectively over the same period, for fluazinam, he said. Untreated plots showed blight infection of 68% by the final assessment, he noted.