The leek moth is an invasive species of European origin that attacks Allium crops (Fig. 1). This pest is particularly a problem in Eastern Ontario. Recently, this pest has been found on pheromone traps* in Central/Southwestern Ontario (Simcoe County, Waterloo Region). Research suggests that this pest will likely spread further south and west from regions where it is currently found.
Damage is due to feeding by the leek moth larvae and damage looks different on the various Allium crops. On hollow-leaved crops, like onions and chives, leek moth larvae enter the leaves to feed internally creating a ‘windowing’ effect (Fig. 2). On flat-leaved crops, like garlic and leeks, the larvae feed on top of and inside of the leaves (Fig. 3) and they may also bore into the leaves creating pinhole damage. On garlic specifically, the larvae will feed on the scapes as well. In some cases, the larva may damage the bulbs.
Pheromone traps can be used to determine the presence and activity of leek moth. It is important to properly identify this pest from other moths and to look for damage in the crop. Typically, traps are installed around the field edge beginning in April. Insecticide applications are timed at 7-10 days after the peak flight. Currently, Warrior and Matador (lambda-cyhalothrin) are registered for leek moth control in garlic, elephant garlic, leek, dry bulb onion, green onion, Welch onion, and shallots. Success (spinosad) and Entrust (organic spinosad) were recently registered on crop subgroup 3-07B (green onions, leeks, chives [fresh leaves], shallots [fresh leaves], bunching onion, tree onion [tops], welsh onion [tops]) for suppression of leek moth; however, these products are not currently registered on crop subgroup 3-07A for leek moth. Please consult labels for directions for use.
Cultural control methods include crop rotation, use of floating row covers (sides of cover anchored to ground), avoiding planting near infested areas, delayed planting, removal of old/infested leaves, early harvesting to avoid damage by populations that have been building up through the season, and destruction of plant debris.
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*funding provided by FVGO