New Pest Targets Virginian’s Onions, Garlic, And Leek Crops

By Devon Johnson and Thomas Kuhar

Home gardeners and commercial farmers alike should be on the lookout for a new Virginia pest: the allium leaf miner, says Tom Kuhar, a professor of entomology at Virginia Tech.

The allium leafminer is an invasive fly that can devastate allium crops like onions, garlic, and leeks. It was first recorded in the U.S. in Pennsylvania in 2015 and was recorded in Virginia in 2021.

“The pest attacks onions, garlic, and leeks where the larvae (maggots) feed on plant tissue by “mining” the plant, causing wilting and possible death,” says Kuhar.

Kuhar says that adult females repeatedly puncture allium leaves with their ovipositor (a tube-like organ for depositing eggs), resulting in a line of small white dots. This may cause leaves to be wavy, curled, and distorted.

“Larvae, which look like a typical whitish maggot, are extremely destructive as they “mine” leaves and move into bulbs and leaf sheathes where they pupate (enter the next stage of their lifecycle),” says Kuhar. “Infected plants may appear wilted or stunted with distorted leaves and smaller bulbs.”

Kuhar says the invasive pest was recorded in Southwest Virginia in 2021 and has been found in Montgomery, Carroll, Botetourt, and Bedford counties. Virginians are encouraged to be on the lookout for this pest and help monitor its spread.

To protect plants, Kuhar says covering crops with agricultural fabric in April-May and September-October, during the adult flights will exclude egg-laying females from reaching your plants and help prevent larval infestations. There are a number of registered insecticide options for commercial growers.  For pesticide recommendations or other information, contact your local Virginia Cooperative Extension Office or consult the Mid-Atlantic Commercial Vegetable Production Recommendations, Virginia Cooperative Extension Publication 456-420 (SPES-391P).

Virginia Cooperative Extension experts help all Virginians implement the research of Virginia’s two land-grant universities, Virginia Tech and Virginia State University, and provide real solutions for a more sustainable and collaborative commonwealth.

To help connect your community with research-based horticulture education and participate in volunteer projects related to emerging pests, environmental stewardship, and community resilience, become an Extension Master Gardener by contacting your local Extension Office.