Allium leafminer feeding damage on onion leaves. Photo: Tim Elkner, Penn State
Based on the amount of observed damage, the population is estimated to be minimal but this indicates that the first adults of the spring generation have now emerged. No evidence of allium leafminer adults was found in a nearby commercial allium planting or during scouting at the Penn State Research Center in Manheim further indicating that we are at the very start of spring emergence. Growers unfamiliar with this pest can get detailed information from the link below.
Any allium crop is at risk for damage or loss from this insect; growers should begin scouting now to determine the need for control measures. Consult the 2018 Mid-Atlantic Commercial Vegetable Production Recommendations for labeled insecticides to control allium leafminer. Any producer planning to use row covers to protect their crop should scout, apply any necessary insecticide, and cover their crops immediately. Grower experience has shown that timely insecticide applications will minimize damage from this pest while unprotected fields have resulted in significant or total crop loss.
Weekly updates on allium leafminer can be heard by calling 1-800-PENNIPM (1-800-736-6476) from a touchtone phone and selecting the allium leafminer update (#8).
This report will be updated weekly during the spring and fall flights.
Allium leafminer fly and feeding damage on leek leaf showing adult size. Photo: Tim Elkner, Penn State