Trials for control of the leek miner fly.
Leek crops in north east Italy have been attacked in the last 5 years by the leek miner fly (Napomyza gymnostoma). Monitoring in 2002 using suction traps revealed that adults fly in March and April with a second generation flying from late September to early November. In spring, the females feed on leek leaves causing small discoloured spots, and then lay eggs. Once hatched the larvae tunnel into the plant giving rise to bacterial infections and ruining the crop. Insecticides applied in 2002 left many surviving larvae, so in 2003 treatments were made earlier, as soon as the first adults were detected. The most effective insecticides were fenitrothion and cyromazine, alone or with an oily wetter.