Corteva Agriscience, the agriculture division of Dow DuPont, says last year’s hot, dry conditions reduced the disease threat in 2018 but could have consequences this season.
The crop protection and seed company says 2018’s smaller tubers and mild winter means growers need to consider strengthening programmes.
Craig Chisholm, Corteva’s field technical manager, said blight spray plans should focus on getting crops off to the best possible start.
He said: “With few rain events from May onwards last year conditions affected tuber size, particularly in unirrigated fields.
“This will mean many small tubers returned to the soil to create the potential for a large volunteer population in the arable rotation.
“The impact will be an increase in the untreated reservoir source. Some volunteers may well come through carrying infection on the stems, providing a ready-made source of late blight.”
Compounding the problem, tight seed supplies may require some growers to consider using home-saved seed which may contribute to an increased risk.
Craig also fears the mild winter weather will not have had a significant effect on discard piles, meaning the potential is there for early and sustained blight pressure in 2019.
“If all these factors combine late blight has the potential to be greater and more aggressive than ever this season,” he added.
Corteva launched Zorvec Enicade (oxathiapiprolin) last year.
Zorvec has unique activity on late blight and, being the first product from a new class of chemistry, has no cross resistance to other active ingredients.
Alongside its proven preventative, persistent and upwardly systemic properties, it is one of the only blight fungicides available to UK growers with curative activity on existential blight.
“When used with an appropriate partner product it will provide control of any late blight from seed or outside sources, including stem blight when applied early in the programme,” Craig said.
“Growers have the option of using Zorvec at 10-day spray intervals instead of the industry standard seven.
“We recommend getting two sprays during the rapid growth phase of the crop to ensure the cleanest possible start to the season, holding one or two treatments in reserve for the stable canopy phase.”