Syngenta say the constant demand of potato crops for water in the hot dry weather is posing a serious headache for growers trying to maintain irrigation scheduling.

The world-leading plant science and crop protection company warn that high levels of water being applied to combat deepening soil moisture deficits poses the real risk of washing off blight fungicides, at the same time creating humid conditions beneath the dense crop canopy that are ideal for disease to develop.

Latest reports from the Met Office highlight the soil moisture deficit this season for the Anglian region – covering key potato growing areas from the east midlands across Lincolnshire and East Anglia – has reached over 95mm, more than 50 per cent higher than typical for the time of year. Most growers are operating at the limit of their irrigation capability, highlights Phillip Ayres, Syngenta Area Manager.

“Growers need to make sure they are using blight fungicide that can withstand heavy irrigation, or sudden summer storm downpours that have become prevalent in recent seasons. Trials and growers’ own experience has shown REVUS to be the most reliable and give the greatest blight protection following irrigation,” he reports.

Trials have shown that even with modest irrigation of 20mm an hour after treatment the performance of cymoxonil and mancozeb was seriously reduced. With an average irrigation application of 40mm, the persistent control with fluopicolide and propamocarb was down below 90 per cent, and when a higher water dose of 80mm was applied its performance rapidly declined to around 60 per cent. REVUS performance was maintained at a consistently high 98 per cent plus control right across all the irrigation programmes.

“Even when blight forecasts based on prevailing weather conditions indicate the disease risk is low, beneath the leafy canopy it can remain hot and humid for several days after an irrigation application – the ideal condition for blight,” warns Mr Ayres. “It’s crucial that growers maintain protection with an effective and reliable fungicide programme.”

REVUS is recognised by independent blight researchers as being the best available product for foliar blight protection. “Its ease of use in practice, coupled with results of over 60 trials showing significantly better and more consistent blight control than other leading fungicides, can give growers the confidence their crops will be adequately protected, no matter when the irrigator passes through or a rainstorm falls,” he adds.