Many potato crops are now emerging alongside intensive weed competition, with continued dry weather conditions having significantly reduced the efficacy of all residual herbicide treatments. The prospect of some limited rain showers this week (26 – 29 April) will trigger a surge of weed activity that could further delay crop growth.
Syngenta Potato Manager, Tom Whitworth, advises the higher available rates of Retro, at up to 4.0 l/ha, will be invaluable for growers seeking to remove larger and more aggressive weed competition this season.
"The rapid growth of weeds could compound the issues of delayed crop emergence in the dry conditions," he warns. "Growers and agronomists will be seeking to control actively growing, vigorous weed populations. The higher rate of Retro will give faster and more robust kill of larger weeds. Cooler temperatures this week will give ideal conditions for Retro application and leave a clean seedbed for rapid crop growth," he adds.
"Retro is the only diquat herbicide approved for use at up to 4.0 l/ha; other diquat products may only be used at a 50% lower 2.0 l/ha label approved rate," reports Mr Whitworth. Retro can be used on maincrop potatoes up to 40% emergence, or 10% emergence of early varieties.
"The higher rate will also be crucial for later planted crops where growers have waited until as close to emergence as possible before applying their Defy residual herbicide, when there may already be significant weed populations established," he said. Trials have shown Defy + Retro tank mix can be safely used up to 10% crop emergence, ensuring the crop can get away in a clean weed free seedbed with the longest possible residual activity.
