The allium leafminer adult population is potentially starting to decline as of the second week of May. We are unsure if this is due to the cooler rainy weather or a true population decline. We suggest leaving row covers on for a long as possible or to continue to use your management choice for at least the next week.
Approximately 2-week old allium leafminer larva that have mined down into the bulb of wild garlic, Allium vineale. Photo: Dana Roberts
Eggs have begun hatching and larva will start to mine in the leaves opening routes for secondary infections. If you see mines, clipping the leaf below the damage will remove that larva. The larvae grow and move quickly through plant material, usually within a week of hatching the mines are easily seen.
Allium leafminer larval mine damage in wild garlic, Allium vineale. Photo: Dana Roberts
For chemical control recommendations, Shelby Fleischer created an allium leafminer amendment for the Mid-Atlantic Commercial Vegetable Production Guide 2016-2017.
For more information about the allium leafminer, including descriptions of the life stages, the Pennsylvania Department of Agriculture and Penn State posted reports and a pest alert to these websites: