Leaf Miner Control
Please always review product labels prior to purchase to confirm the product you are purchasing is labeled for the specific pest/disease & crop you are treating.x
FOR YOUR FILES: Leaf Miner Tech Sheet (PDF)
Photo courtesy of University of Wisconsin
- Leafminers belong to several different genera of insects such as beetles, flies, and moths. It is simple to identify a leafminer as they ‘mine’ through the leaf and cause damage that is fairly unmistakable. As larvae tunnel their way through the leaf layers eating chlorophyll and other plant juices, they leave a white winding trail behind.
Scouting can be done during the day when there is light to see these symptoms. Although leafminers rarely kill a host outright, they can ultimately
weaken the plant’s ability to photosynthesize, which can result in stunted growth, discoloration, or even open a wound for which disease can enter. Also, in the case of leafy greens such as lettuce and spinach, leafminer damage can cause the crop to become less profitable. - A variety of vegetable crops, but can be particularly harmful to leafy greens such as spinach, lettuce, etc. They also tend to enjoy Aquilegia spp., which is also mentioned below for its utility as a trap plant.
- Females lay eggs underneath the plant’s epidermal layer on the leaves. Larvae hatch and burrow through the leaf tissue feeding on chlorophyll. After 2-3 weeks they are ready to pupate and burrow into the soil where they will emerge roughly two weeks later as adults. Multiple generations can occur each year.
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Beneficial Insects:
Steinernema feltiae is a beneficial nematode species that can be an effective biocontrol. These parasites can be applied to the soil to infect and help control an array of soil-dwelling pests. Leafminers overwinter in the soil as pupae, giving nematodes the opportunity to pounce, while not harming other beneficial inhabitants in the soil.
Diglyphus isaea is a parasitic wasp that stings and paralyses the leafminer larva while it is feeding in the leaves. Diglyphus spp. lay their eggs alongside the host, and after the eggs hatch they feed off the fluids of the still alive but paralyzed larva. Each female wasp can kill over 300 leafminer larvae!
Insecticides:
Products where Neem oil is listed as the main ingredient are great for spray applications.
(Other product labels that target leafminers include):
Grandevo, Azatin O, PyGanic, Molt-X, PFR-97, and Venerate XC.
Cultural Control & Further Considerations:
Leafminers tend to enjoy Aquilegia spp., so consider utilizing these ‘trap’ plants in adjacent areas to the field in order to draw leafminers away from vegetable crops.
To encourage Diglyphus isaea in your system, plant flowers such as dill and yarrow, which are rich in pollen and nectar, giving the wasps an accessible food source.
Always obtain an accurate diagnosis and ensure you are using good cultural and sanitation practices. Local extension offices will generally be able to identify your pest. Additionally, feel free to send us images and we will do our best to assist you.
