15 May 1998

Take care with strobs

STROBILURIN fungicides need using with care and in many cases older chemistry could give excellent disease control at less cost and with less risk for the grower.

That is because strobilurins are mainly protectant products, offering very little eradicant control of foliar diseases, warns ARC director Mike Carver.

"Last year opened our eyes – we realised that in themselves strobilurins are not as good fungicides as triazoles. If you treat them like a triazole fungicide you are heading for disaster," Dr Carver warns.

"The danger is that there just isnt the kick-back activity there. Each new triazole offered more protectant and more eradicant activity than the one before. That just isnt the case with the strobilurins."

In certain high yielding situations strobilurins can give a definite yield benefit, provided the farmer knows how to use them, he continues. "But dont forget you have some superb old chemistry, like epoxiconazole, which can give protection and kick-back control of most foliar diseases."

He urges growers to consider timing carefully and look at mixture partners. "Also avoid spreading supplies too thinly. If you have some strobilurin use it close to full rate. I firmly believe the dose rate response is a real one – you cant reduce rate much even where you are mixing with a triazole like epoxiconazole."