Leek Moth Update - 1 August 2012

In 2011, leek moth pheromone traps were installed in Allium growing areas across southwestern and central Ontario. This pest was found in York Region, Simcoe County and Waterloo Region.

In 2012, a similar monitoring program has been set-up in garlic and leeks in various counties/regions across southwestern and central Ontario. From mid-April to the beginning of May, a total of 4 leek moth from the first flight were caught in the traps in Waterloo Region. We saw 2 leek moth in the traps during the first week of July at this site. During the second week of July, a single leek moth was captured in Brant County. Although these numbers are 'low' relative to other areas, it is important to learn more about this pest as it spreads.

Most of the garlic in this region is harvested; however, keep an eye out for 'exit' holes from the bulbs (Fig 1). Green Allium crops that are still in the ground are susceptible to this pest, so also keep an eye out for damage, larvae and pupae. Remember that pheromone traps attract the adult male leek moths; however, it is the larval stages of this pest that causes the damage.

Fig 1. Two leek moth exit holes

Fig 1. Two leek moth exit holes

Management Options

Pheromone traps can be used to time organic pest control products with applications timed 7-10 days after the peak flight (See Table below). Entrust (organic spinosad) is registered on crop subgroup 3-07B for suppression of leek moth; however, this product is not currently registered on crop subgroup 3-07A. Crop subgroup 3-07A includes garlic and dry bulb onions and we are still awaiting the registration of Entrust on this crop subgroup. Refer to the label for directions for use.

Active ingredient
Crops PHI (pre-harvest interval) Pest on Label Notes

Entrust 80 W


Crop subgroup 3-07B (green onions, leeks, chives [fresh leaves], shallots [fresh leaves], bunching onion, tree onion [tops], welsh onion [tops]) 3 Suppression of leek moth larvae Group 5 - spinosyn
Apply one week after peak pheromone trap captures for leek moth. Evening applications provide better control.
Entrust 80 W is organic. Check with certification body before use.
Max of 3 applications/season.

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 (burn or bury, if possible!).
Floating row covers have been used with success in the Eastern parts of the province to protect the plants from leek moth. It is important to anchor down the sides to prevent leek moth from entering the covered row (Fig 2).

Fig 2. Floating row cover on some garlic plots. Note that the sides of the row cover are anchored down. (Photo: Andrea Brauner, AAFC)

Fig 2. Floating row cover on some garlic plots. Note that the sides of the row cover are anchored down. (Photo: Andrea Brauner, AAFC)

More on Leek Moth

The leek moth, Acrolepiopsis assectella, is an invasive species of European origin that attacks Allium spp., including garlic, onions and leeks. Since its detection in 1993 in the Ottawa Region, the leek moth has been a problem for commercial Allium growers and particularly to organic market garden producers in the region. Research by Peter Mason's group from Agriculture and Agri-Food Canada suggests that this pest will likely spread further south and west from regions where it is currently found. Since 2009, leek moth has been detected in a few counties of northern New York State and in Vermont.

If you suspect leek moth, please call Marion Paibomesai, Vegetable Crops Specialist, OMAFRA at 519-826-4963.

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For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca