WHILE THIS season’s late planted potato crops might have been slow to get going in cool soils, recent rapid growth in warmer conditions also mean increased blight pressure.

That means protecting expanding leaf area with the strongest blight fungicide active, mandipropamid (Revus), is more important than ever, according to Syngenta's potato technical manager, Douglas Dyas.

“When the crop’s initial growth has been held back, the area of a new potato leaf could more than quadruple in the course of a week during the rapid growth phase,” he reported. “That puts immense strain on blight fungicide protection between applications.”

Revus locks onto the plant’s leaf wax and, as the leaf area expands, the active moves across the surface to protect it against blight infection, he argued.

This action helps ensure protection between sprays, even where application may be delayed.

Douglas added it was clearly evident that where the early Revus-based programme had completely kept blight out of the crop, it remained clear for longer when the trial applications finished, compared to a fenamidone + propamocarb and fluopicolide + propamocarb early programme, where blight established sooner and developed faster, despite relatively low levels of blight infection.

“The trials have confirmed the importance of the early blight sprays when potato plants are growing rapidly. Whatever the blight pressure, growers cannot afford to risk letting disease establish in the crop.

“Investing in strong blight performance early season pays dividends in producing a cleaner crop at the end,” he added.