Raspberry cane midge

Raspberry cane midge (Resseliella theobaldi) is a significant pest that causes severe damage to raspberry plantations, often leading to a condition known as midge blight. The injury is caused by larvae feeding on the stem tissues, which facilitates the entry of pathogenic fungi into the plant.

The primary host for this pest is the red raspberry. The larvae live under the epidermis of young canes, disrupting the flow of nutrients. As the tissues die, opportunistic fungi infect the cane, causing it to weaken and eventually collapse, which severely limits the plant's yield potential.

Symptoms include distinct dark, sunken lesions on the lower portions of the canes. As the infestation progresses, these areas crack and become necrotic. Growers often notice the leaves wilting or the canes snapping off at the point of damage, especially during windy conditions or when heavily laden with fruit.

The development of midge blight is heavily influenced by climatic conditions. High humidity and moderate to warm temperatures favor the lifecycle of the midge, allowing for multiple generations per season. The presence of cracks in the cane bark, often caused by cold or mechanical damage, significantly increases susceptibility.

• Remove and burn infested canes in late winter.
• Apply targeted insecticides during the adult emergence window.
• Maintain proper spacing to ensure adequate air circulation.
• Avoid unnecessary mechanical damage to the canes during cultivation.

Effective management requires a combination of sanitation and chemical intervention. By destroying the overwintering larvae in infested stems and timing insecticide applications correctly, growers can significantly reduce the pressure of this pest and minimize the economic impact on the harvest.