Application should coincide with emergence of first-generation adults before they lay eggs. A blackberry leaf midge sex pheromone trap has been developed but its use for timing sprays had not been investigated.
AHDB Horticulture (formerly HDC) project SF 141, led by East Malling Research, sought to find the most effective spray timing and screen approved products for blackberry midge control in crops of protected raspberry.
A replicated field trial was conducted to examine the effects of single applications of chlorpyrifos or deltamethrin to control blackberry leaf midge. The trap was checked twice weekly and the sprays were applied one, three, seven and 14 days after a catch of 10 male midges per sex pheromone trap per week was exceeded.
Blackberry leaf midge sex pheromone monitoring traps proved a useful tool for timing applications of chlorpyrifos and deltamethrin. Early applications (within seven days of the trap threshold of 10 midges per trap being exceeded) gave good levels of control in raspberry crops.
Where applications were made more than seven days after the threshold was exceeded, control of midge larvae deteriorated. Checking the trap twice weekly gave the opportunity to plan spray applications and ensure the peak of the first generation was controlled.
The latest report for project SF 141 can be found online at www.horticulture.ahdb.org.uk.
For details on all AHDB Horticulture activity, see horticulture.ahdb.org.uk