Potato herbicide timing to dry soils

Potato growers will need to adapt herbicide application options and timing to cope with dry soils this spring, with the best option for Defy + Retro at the point of emergence, advises Jon Ogborn of Syngenta Crop Protection in the UK. Exceptional April weather conditions has seen potato planting continue almost uninterrupted by rain – with over 85% of the area now estimated to be in the ground and many crops already starting to emerge.

But the record temperatures and warm winds have dried soil surfaces to the point where the full effect of all residual herbicides may be adversely affected, warns Jon Ogborn of Syngenta. “Growers experience and trials last year – when conditions were similarly dry after planting – highlighted the best results could be achieved with Defy applications at or as close to emergence as possible,” he advises.

“With crops emerging rapidly in the warm seedbeds, growers are going to have to be on the ball with application timing this year.” Growers are reminded that Retro is the only contact herbicide option permitted once the crop has emerged.

Mr Ogborn advocates that for early applications, soon after planting, growers should opt for Defy at 4.0 – 5.0 l/ha + metribuzin. Where linuron is used, the rates must be no more than the 1.2 l/ha of 50 % formulation (or 1.33l/ha of 45% formulation) now permitted, he adds. “Where early residual combinations have been used in the current dry conditions, growers must keep a watchful eye on crops and top up with a contact if they see weeds emerging. As this will be close to crop emergence, Retro is the only option.” 

Rainfall of up to 10mm forecast for western counties of the UK over the coming days (25-27 April) will have a significant effect in enhancing the residual activity of Defy and partner products, with the real chance for growers to clean up this spring. But eastern counties are set to remain virtually dry for the foreseeable future.