Potato crops that have been held in check by the cold weather are expected to put on a surge of new growth after any rain or irrigation when conditions warm up. But a rapid expansion in the leaf area will stretch the protection of blight fungicides, at a time when risk is likely to significantly increase, warns Syngenta Technical Manager, Stephen Williams.
He advocated growers and agronomists should be looking to utilise the movement of Revus fungicide into expanding leaf growth, to offer extending protection from infection between applications.
“New leaf growth is especially susceptible to infection,” advised Mr Williams, “partly since the soft tissue is easier for the pathogen to infect, but also because it is unprotected by conventional contact fungicides. Furthermore, their efficacy is reduced over time after each application.
“Revus will move with the expanding leaf to offer protection of the new surface area. It is also highly effective at maintaining protection between applications.”
Revus is proven in trials as the leading blight fungicide for protection against foliar infection. Maintaining a clean leaf in the early stages is essential to prevent disease developing later in the season, as well as stopping transfer of blight to tubers, added Mr Williams.
Mr Williams pointed out that new criteria for foliar blight prediction on the Syngenta website BlightCast service had already indicated the potential for infection in the crop this season. The forecast triggered potential infection periods at lower temperatures, believed to be more representative of today’s more aggressive blight strains.
BlightCast provides a free localised forecast for growers and agronomists, based on both traditional Smith Periods and the New Criteria, to help with better timing and selection of appropriate blight fungicide programmes.
