What can I do to save my garlic plants from the Alium Leaf Minor ? - Ask Extension
Looks like I have infestation of Alium leaf in the many garlic plants I have in Westminster? Can I save these plants at all ? I have organic garden s...
Knowledgebase
What can I do to save my garlic plants from the Alium Leaf Minor ? #867260
Asked May 06, 2024, 2:16 PM EDT
Looks like I have infestation of Alium leaf in the many garlic plants I have in Westminster? Can I save these plants at all ? I have organic garden so I’m restricted. Can I talk to someone ? Thank you. Curt
Carroll County Maryland
Expert Response
Hello Curt,
You can use an organic pesticide like one containing the active ingredient spinosad, which absorbs into leaves, to kill the young larvae of Allium Leafminer. That is, if the symptoms of egg-laying, as you pictured here, are less than 2 weeks old; otherwise, the larvae may be too mature or down towards the bulb to be affected well enough by a treatment. To prevent future infestations, since this pest has two generations per year in Maryland, you can cover the crop ahead of each emergence period (February and September for placing row cover on) to block access to the egg-laying adult flies.
Miri
You can use an organic pesticide like one containing the active ingredient spinosad, which absorbs into leaves, to kill the young larvae of Allium Leafminer. That is, if the symptoms of egg-laying, as you pictured here, are less than 2 weeks old; otherwise, the larvae may be too mature or down towards the bulb to be affected well enough by a treatment. To prevent future infestations, since this pest has two generations per year in Maryland, you can cover the crop ahead of each emergence period (February and September for placing row cover on) to block access to the egg-laying adult flies.
Miri
Thankl you Miri for your answers and recommended actions! I will definitely try out the Organic pesticide you recommended. Can you answer these additional questions please ? What actions can I take for damage control of the Allium Leafminer. Can I harvest earlier than normal to minimize damage ? Would cutting the leaves now make sense if they haven't emerged yet ? I assume covering the Garlic now is too late since they ALL seem to be infected. ? I will also plan to cover the beds in September and February. I was also thinking of covering the beds in July with clear plastic to kill the insects ? Would this work ?
Thanks.
Curt
You're welcome.
Harvesting earlier is not really useful as it would detract from the bulb's harvest size and the larvae would already have gone further down into the lower growth by that point, still potentially ruining (at least part of) the harvest. You would not want to remove leaves prematurely since they are needed to feed the bulb via photosynthesis; so little of the foliage is damaged by the leafminer larvae that the rest of the affected leaves are still contributing a lot of energy to bulb development.
Yes, covering the garlic plants now is too late; it needed to occur back in late winter, around February or so, which is just before when the adult flies were out laying eggs. There are no egg-laying adults out now. Covering empty beds with plastic might have some benefit if we have weather hot enough to solarize the soil surface and heat it up, but it would be simpler to just till or fork the soil a bit to bury or expose the pupate that way, where they will either die or be eaten by predators like birds or predacious ground-hunting beetles.
Miri
Harvesting earlier is not really useful as it would detract from the bulb's harvest size and the larvae would already have gone further down into the lower growth by that point, still potentially ruining (at least part of) the harvest. You would not want to remove leaves prematurely since they are needed to feed the bulb via photosynthesis; so little of the foliage is damaged by the leafminer larvae that the rest of the affected leaves are still contributing a lot of energy to bulb development.
Yes, covering the garlic plants now is too late; it needed to occur back in late winter, around February or so, which is just before when the adult flies were out laying eggs. There are no egg-laying adults out now. Covering empty beds with plastic might have some benefit if we have weather hot enough to solarize the soil surface and heat it up, but it would be simpler to just till or fork the soil a bit to bury or expose the pupate that way, where they will either die or be eaten by predators like birds or predacious ground-hunting beetles.
Miri
