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Hot weather triggers Sclerotinia risk rise

Product Update
OSR coming into flower

Sclerotinia sprays will be the key focus for oilseed rape crops over the next three to four weeks. The risk has been low up until now, with soils too cold to trigger apothecia into significant spore release. But, with temperatures climbing and settled conditions, infection pressure is now escalating rapidly.

Syngenta Field Technical Manager, James Southgate, urged growers to make Amistar applications now, if they have not yet already applied a Sclerotinia treatment. “There is still ample soil moisture and damp conditions within the crop canopy to allow infection to develop. All Sclerotinia fungicides work most effectively when applied prior to infection,” he advised.

“The key advantage with Amistar is that, if it stays very dry and infection doesn’t occur, crops still get the benefit of the greening effect and healthy leaf retention,” said James Southgate.

“That drives economic yield and valuable improved oil content of seed for higher margins.”

With significant Light Leaf Spot infection on lower leaves and the effects of CSFB infestation many plants already have damaged or decaying vegetative material at the bottom of the crop canopy – which could create ideal conditions for Sclerotinia infection (below).

James (above) advocated that, where Light Leaf Spot is still active when the flowering spray is made, a good solution would be to tank mix prothiaconazole with the Amistar at 0.5 – 0.8 l/ha.