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Invasive Allium Leafminer - Located in Washington County, MD #638630

Asked May 20, 2020, 7:03 PM EDT

Hello - I am contacting you from Hagerstown, Maryland and I have a plot at our community garden here. Allium Leafminer is an invasive species that targets allium plants (onions, leeks, & Garlic). To my knowledge there have been no prior confirmed cases in washington county, so I wanted to reach out and let you know that we found them in our garden this evening. Here is the research on this from Pennsylvania Dept. of Ag: https://www.agriculture.pa.gov/Plants_Land_Water/PlantIndustry/Entomology/Pages/ALLIUM-LEAFMINER.asp...

Washington County Maryland

Expert Response

Hi - Thank you for submitting your photos. Yes, this appears to be allium leafminer. We have a faculty member who is tracking locations where it is reported in Maryland and I will let him know about your report; thank you.

These insects pupate in protected plant parts (bulbs, leaf sheaths) and a second
generation of adults emerges in September and lays eggs. Larvae feed and
overwinter in the pupal stage inside infested plants and adjacent soil. We suggest you remove and discard the plants. Here is our information about this new pest. https://marylandgrows.umd.edu/2017/10/14/allium-leafminer-possible-ornamental-plant-pest/

If you re-plant, a floating row cover can be used to exclude the adults in spring and fall when they are flying and searching for host plants. You found good information from the PA Department of Agriculture. Penn State University is also conducting research on this new pest and has very good information about it. https://ento.psu.edu/extension/vegetables/pest-alert-allium-leafminer

Christa
Answered by the Home & Garden Information Center's Maryland Certified Professional Horticulturists Replied May 21, 2020, 11:45 AM EDT

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