Increasing blight pressure means potato growers need to protect crops against foliar and tuber blight, experts have advised

Early control from stable canopy to senescence based on a spray programme including products with proven zoospore activity will be most effective, said Dow AgoSciences’ principal biologist, Andy Leader.

“From mid-season onwards as soon as tubers are being formed, blight sprays need to provide protection against foliar blight as well as tuber blight. Zoospores are the causal agents of tuber blight and these mobile spores can be produced from now on, usually when temperatures get below 15ºC.”

Even where there are low levels of foliar blight at the end of the season, there can still be a high risk of tuber blight, he added.

“You only need a few zoospores to be formed and released to the soil for tubers to suffer significant and damaging blight infections. The best spray programmes include products with proven zoospore activity from stable canopy to senescence.”

He suggests using Electis, which (according to BPC trials) gave the best foliar and tuber blight control when used in a programme consisting of two treatments of Epok (mefenoxam + fluazinam), followed by Electis from stable canopy onwards and then alternating with Ranman TP (cyazofamid plus adjuvant) until desiccation.

See www.potato.org.uk for the latest ‘Fight against blight’ reports and blight outbreaks.