New Late Blight Strain in UK requires Fresh Approach to Control

Late Blight control strategies in the United Kingdom will have to change this season if potato growers are to combat the spread of a new aggressive, fungicide-insensitive/ resistant strain of the disease, leading agronomy firm Hutchinsons says.

The dark green 37_A2 form of Phytopthora infestans has quickly spread across Europe, reaching England two years ago when five cases were reported.

The key is to rotate chemistry and keep spray intervals tight, typically seven days. If blight pressure is very high it may even be worth applying an intermediate spray, he says.

Andrew Goodinson:

“If it’s a high pressure season, we may not use any fluazinam at all.”

“However, fluazinam in the middle of the programme is quite good for sclerotinia and other stem issues, so if pressure is lower it may still be a cost-effective option for crops not going into store.”

If fluazinam is used, Mr Goodinson says a robust rate must be applied and it should be mixed with an effective blight product.