Light leaf spot fungicide performance results available

FUNGICIDE performance results for light leaf spot are now available from HGCA.

Light leaf spot has become more prevalent in England in recent years and, according to Rothamsted Research, this trend is set to continue. If the disease was well established on-farm before harvest in 2012 then there is a high risk of further problems in 2013. November is an important month for monitoring this disease and spraying if the disease risk is high.

HGCA fungicide performance trials, which started in 2009, show good control of light leaf spot is difficult to achieve. Azoles are the leading fungicides but reduced sensitivity to these products may be affecting performance. There are some differences between products but prothioconazole remains the leading active. However, product choice will also be affected by the need for plant growth regulation and phoma treatment.

No improvement

The trials show no improvement in control with more than half dose rate applications, so control is unlikely to be improved with high doses. There are, however, prospects for improving control with better timing as many crops are treated when the disease is already well established.

Advice, based on the trials findings, is to spray in autumn at high-risk sites and after the autumn treatment inspect crops for light leaf spot regularly on a field-by-field basis. If phoma sprays are being used, check crops in winter and early spring to determine if the sprays have given adequate control of light leaf spot.

Before stem extension in spring, apply fungicide as soon as light leaf spot is found. The findings also suggest during the early stem extension stage growers should spray when 15 per cent of plants are affected.

The full summary report is available at

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