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Be on alert for fungal disease in strawberry crops

High pressure from fungal diseases, such as Botrytis and powdery mildew, are expected in strawberry crops, following a wet autumn and mild winter.

High pressure from fungal diseases, such as Botrytis and powdery mildew, are expected in strawberry crops, following a wet autumn and mild winter.

Dennis Wilson of Delphy UK, explains why an integrated approach for controlling fungal diseases, combined with a strict post-winter cleaning policy, is essential to reduce the risk imposed by increased pressure. 

“Last season brought perfect conditions for fungal diseases to survive. The wet weather also disrupted spray programmes, which made it difficult to control any outbreaks in the autumn and is likely to have resulted in disease carry-over,” explains Mr Wilson.

Integrated step-by-step approach

“Growers need to be vigilant as the weather begins to warm up and consider a three-step strategy to prevent build-up of disease.

“Step one should be to carry out a thorough clean up. Removing old leaf trash which may harbour over-wintered spores and any decaying fruit and crown tissue is vital, as these provide the perfect habitat for diseases to thrive.

“This should be followed by a regular spray programme of protectant fungicides, based on risk and conditions.

“The final step for those growing under protection is to manage the climate. Increased heat and humidity favours fungal spore growth, so monitor these carefully throughout the growing period, and try to make adjustments by timely ventilation,” he adds.

Dennis’ top tips for fungal disease control:

  • Start clean, stay clean – remove any infected or dead leaves as these provide the perfect habitat for fungal growth
  • Rotate modes of action to prevent resistance build-up in the crop. Consider Frupica SC when the crop reaches the early flowering stage for prevention against both Botrytis and powdery mildew
  • Consider your spray interval – use growing degree hours (GDH) to measure intervals to take in to account the changing growth rate of the plant. A spray interval of 1,500 GDH will ensure that you are always protecting the new leaf
  • Ensure that the relative humidity is controlled during the day at around 60-75% to reduce disease pressures