A review of control measures for blackberry downy mildew

Why the need for a review?

Recent losses of effective spray products, particularly close to harvest, have made it increasingly difficult for growers to gain control of downy mildew in blackberry. AHDB commissioned a desk study to review novel and alternative approaches, which might be relied on in future.

Key findings

  • All forms of protected cropping will reduce leaf wetness and minimise infection.
  • Before establishing a new crop, choose a site that avoids natural sources of infection, maximises light interception and maintains good air movement.
  • Reduce relative humidity in protected crops to below 85%. This can be achieved by reducing weed growth, maintaining adequate venting and where necessary, using air fans in glasshouse crops to improve air movement.
  • Manage nitrogen and other nutrition carefully to avoid excessive vegetative growth.
  • Photoselective polythene to alter the wavelength of light reaching the crop could affect the infection rate, but this requires further study.

Further reading