Keep an Eye Out for Allium Leafminer

Spotted lanternfly ( Lycorma delicatula ) is get a lot of attention as the latest big pestilence terror in the Mid - Atlantic , but it ’s not the only new and serious job to pop up in our area recently . Allium leafminer ( Phytomyza gymnostoma , orNapomyza gymnostoma ) , also screw as onion plant leafminer , is another invasive insect to find out out for in your garden . Native to piece of Europe , it was first distinguish in this land in Lancaster County , Pennsylvania , in recent 2015 , and as of this bounce , genus Allium leafminer has been identified in New York , New Jersey , Massachusetts , and Maryland as well .

As indicated by the name , this gadfly affects middling much any mintage of genus Allium . Besides victuals like onions , leeks , garlic , chives , and shallots , it can also damage ornamental alliums . I first noticed its presence in my Bucks County , Pennsylvania , garden last summer , and the grownup appear again this year the last hebdomad of April , make feeding damage on my even onions ( Allium cepa , Zones 5–10 ) , Egyptian or top - place onions ( A.×proliferum , Zones 3–10 ) , hardneck garlic ( A.sativumssp.ophioscorodon , Zones 4–9 ) , and ‘ Forelock ’ decorative onion plant ( A.‘Forelock ’ , Zones 4–8 ) .

The adult flies are very small — larger than a yield fly ball but smaller than a housefly — so you may not even discover the insects themselves , but their distinctive feeding and egg - laying legal injury is easy to spot . The female use their ovipositor to perforate holes in the leave of absence , and they and the male feed on the exudate . This activity appear on the upper part of the farewell as a line of small , pallid dots ; that ’s mostly cosmetic harm , though . The females also lay egg just under the Earth’s surface on the grim part of the foliage . The eggs then hatch , and the larvae tunnel downwardly , feeding as they go . Their eating can cause leaf distortion and also make the works more susceptible to bacterial and fungous diseases , potentially to the breaker point of make the intact crop unusable .

The genus Allium leafminer is so unexampled here that researchers are skin to investigate the best routes for manipulate it . Right now , there are n’t many options , particularly for home base gardeners . If you ’re growing only exclusive - season genus Allium crops , like onions , it may be enough to plant a couple of weeks afterwards than usual to miss the first genesis of adults . If you ’re growing eatable alliums that will have foliage in late summertime or early dusk ( when the second generation of grownup emerges ) and/or in spring — leek , garlic , and cive , for example — using row covering can prevent the adult fly from feed and lay eggs on the leaves . That wo n’t assist on decorative kinds , though . There ’s not much point in growing the big , gorgeous globes of ‘ Gladiator ’ blossoming Allium cepa ( Allium‘Gladiator ’ , Zones 4–7 ) and other show - stoppers if you have to cover them up !

If you growanykinds of genus Allium in your garden , keep your center out for more information on the status of this pest as it moves throughout the Mid - Atlantic region . count check the website for your state of matter ’s conjunctive lengthiness service every few months to keep up with the up-to-the-minute newsworthiness on this gadfly in your particular area .

Nancy J. Ondra is the generator of over fifteen books , includingGrasses , The Perennial Care Manual , andThe Perennial Matchmaker .

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