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Be alert for Spotted Wing Drosophila in soft fruit

Certis are recommending that monitoring for Spotted Wing Drosophila (SWD) should begin in April, and continue through to November.

Certis are recommending that monitoring for Spotted Wing Drosophila (SWD) should begin in April, and continue through to November.

“Although, to date, numbers in the UK have been low, it remains important to stay alert,” says Certis’ Alan Horgan.

“Pest traps containing a sugary solution to which the SWD is highly attracted, are ideal for catching and monitoring the pest,” he adds, noting that growers are in the unique position to ensure any possible incidence of infestation is monitored and the implication understood as early as possible.

Trap locations:

• Consider areas of risk e.g. near the edges of crops, near hedges and vulnerable crops
• Stone, cane and bush fruit - hang the traps at one third of the canopy height
• Outdoor strawberry - hang on a post above the ground and below the spray boom height
• Tunnel strawberries - hang in the leg row at a height of 10cm

Pest identification:

• SWD look similar to the common fruit fly (Drosophila melanogaster)
• SWD is indistinguishable by its larvae, but most characteristics on the adults are visible to the naked eye, although a hand lens is useful
• Males have a large spot along the front edge of each wing and two dark sex combs on the forelegs
• Females have an unusual serrated ovipositor allowing it to penetrate the skin of fruit

Further advice:

• Good crop hygiene helps prevent SWD:
- Remove all non-saleable, dead or damaged fruit
- Store all waste fruit in a sealed, release valve container
• Very few SWD effective insecticides are available to the soft fruit industry:
- Rotate modes of action wherever possible
- Apply Integrated Pest Management (IPM) principles