Blackberry leaf midge or Dasineura plicatrix has become an increasingly important pest of l blackberry and raspberry crops in the UK and across Europe. Once considered as a relatively minor problem, it is now attracting greater attention from growers because of its ability to disrupt cane development, complicate crop management and reduce yield. The adult is a tiny, mosquito-like fly, around 3 mm long, with clear wings and long, slender antennae. The adult populations are generally known to peak in July. 

The greatest concern for growers is the damage caused to primocane shoot tips. Midge feeding stunts the growing tip and encourages abnormal branching, resulting in poorly developed canes that are more difficult to train. This can have consequences beyond the immediate damage such as poorly positioned or weakened canes can reduce the plant’s photosynthetic capacity, interfere with subsequent crop development, and renders the plants more vulnerable to low-temperature damage. As cane structure is fundamental to managing the blackberry crops, repeated midge damage can ultimately affect fruit production. According to growers, it is estimated that blackberry leaf midge can easily reduce yield of blackberry crops by 10%, leading to losses of £3,000 per ha on a typical 15 t/ha blackberry crop. Given this potential economic impact, early detection is extremely important. Pheromone traps provide a proactive approach by monitoring adult male activity and giving growers an indication of when populations are building. Research into species-specific pheromone traps has shown potential in identifying the timing of midge activity and helping growers target treatments more precisely.  

If used alongside monitoring, the following approach can help suppress populations before they become a threat. D. plicatrix larvae eventually leave the plant and enter the soil to pupate, disrupting this stage of the life cycle can help reduce future populations. Ground covers, including suitable nylon fabric sheets, can form a physical barrier between the crop and soil surface. They can restrict adult emergence and prevent larvae from reaching suitable pupation sites thereby exposing them to predators and reducing their numbers from developing further.  

Adult midges are considerably more exposed than larvae feeding within distorted leaf tissue, so targeting the adult stage or newly emerging larvae offers a better opportunity for control. Spinosad has demonstrated significant activity against blackberry leaf midge, while azadirachtin and Bacillus subtilis-based products have also shown promise in soft-fruit systems. However, performance can vary according to product, formulation, application timing and pest pressure. 

As the demand for crops with minimal or zero pesticide residues increases, instead of repeating broad-spectrum applications, growers can combine pheromone monitoring, regular inspection of young shoot tips, cultural measures such as ground sheeting, conservation of natural enemies, and carefully timed biological-based interventions.  

It is important to note that successful blackberry leaf midge management depends on breaking the pest’s life cycle. Targeting the first generation is particularly valuable because reducing early-season populations can limit the number of midges contributing to later generations. Besides, cultural control can reduce the pest’s ability to complete its development, and precisely timed treatments can deal with populations that exceed acceptable levels to maintain yields and meet the increasingly stringent residue expectations. 

References 

UK: Pheromone trap prevents grower from 40% crop losses
SCEPTREplus: Cane fruit | AHDB  Appendix 3
Dasineura plicatrix 

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