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 (See Leek Moth – Update for photos of damage on foliar tissue).

Fig 1.  Two leek moth exit holes

Management Options

Pheromone traps can be used to time insecticide applications with applications timed 7-10 days after the peak flight (See Table below). Success (spinosad) and Entrust (organic spinosad) are registered on crop subgroup 3-07B for suppression of leek moth; however, these products are 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/Success on this crop subgroup. Notice that Delegate WG and Success 480 SC are in the same insecticide group (group 5 – spinosyns). In order to prevent resistance, it is important to rotate between different groups of insecticides. Refer to labels for directions for use.

ProductActive ingredient Crops PHI (pre-harvest interval)  Pest on Label Notes
Warrior, Matador 120 EClambda-cyhalothrin

 

garlic, elephant garlic, leek, dry bulb onion, green onion, Welch onion, and shallots 14  Control of leek moth Group 3A – pyrethroidApply in 500 L/ha of water.

Max of 3 applications/season.

Success 480 SC, Entrust 80 Wspinosad

 

 

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 – spinosynApply 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.

Delegate WGspinetoram

 

Crop group 3: garlic, great-headed garlic, leek, dry bulb onion, green onion, Welch onion and shallot 3  Suppression of leek moth Group 5 – spinosynUse higher rates when insect pressure is high or insects are in advanced growth stages.

Apply one week after peak pheromone trap captures for leek moth. Targets hatching eggs and small larvae.

Max 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)

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.

Resources

Refer to Ontario CropIPM online at http://www.omafra.gov.on.ca/IPM/english/onions/insects/leek-moth.html

OMAFRA factsheet—Leek Moth—A Pest of Allium Crops http://www.omafra.gov.on.ca/english/crops/facts/08-009.htm for more information.

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

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