Cabbage root maggot? - Ask Extension
Hello,
I plant ornamental cabbages I get from the Friend's School Plant Sale each year. I was planting a few today and I started to dig up non-modal m...
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Cabbage root maggot? #455414
Asked May 20, 2018, 5:49 PM EDT
Hello,
I plant ornamental cabbages I get from the Friend's School Plant Sale each year. I was planting a few today and I started to dig up non-modal maggots of some sort. I did an internet search. Are these cabbage root maggots? It's weird because they are highly concentrated in just one spot. I will attach pictures. They are very small, about 1/4 inch and range in color from pale tan to light brown to red. What can I do to get rid of them, as organically as possible? I don't use nasty pesticides. Thanks for your help. I've never seen them before.
Ramsey County Minnesota
Expert Response
Based on your description and what we can see in the photos, we think you have found cabbage root maggot pupae. The tiny white larva damage the roots of newly planted and developing cole plants.
This bulletin describes the maggot's life cycle and recommends controls:
https://www.vegedge.umn.edu/pest-profiles/pests/cabbage-maggot
Some gardeners use row covers to keep the flies from laying eggs near transplants.
If your ornamental cabbage has been damaged severely, it's not too late to re-plant.
This bulletin describes the maggot's life cycle and recommends controls:
https://www.vegedge.umn.edu/pest-profiles/pests/cabbage-maggot
Some gardeners use row covers to keep the flies from laying eggs near transplants.
If your ornamental cabbage has been damaged severely, it's not too late to re-plant.
Bob,
Thanks for getting back to me so quickly. Is the only way to get rid of the maggots to dig them up, then make a "collar" for each plant? Or should I just plant the cabbage somewhere else for this year? I'm finding them in a concentrated area in a small section of the yard ringed by my house and sidewalk.
Thanks for getting back to me so quickly. Is the only way to get rid of the maggots to dig them up, then make a "collar" for each plant? Or should I just plant the cabbage somewhere else for this year? I'm finding them in a concentrated area in a small section of the yard ringed by my house and sidewalk.
On second thought, we think the pupae may not be cabbage root maggots. These pests are associated with cole crop roots so we'd expect you to find them sometime after planting the cabbage, not before. If cole crops have not been grown before in the section of the yard you mentioned, that makes the presence of cabbage root maggot pupae even more unlikely.
If the pupae are not cabbage maggots, their presence does not preclude planting cole crops there.
If the pupae are not cabbage maggots, their presence does not preclude planting cole crops there.
Hi Bob,
I grow ornamental cabbage in that same spot each year. Can the maggots over-winter in the soil?
I grow ornamental cabbage in that same spot each year. Can the maggots over-winter in the soil?
Yes, according to information in the following bulletin, "cabbage maggots overwinter as pupae in the upper few inches of the soil. In early May, adult flies emerge and lay eggs on the soil near the base of cole crops. Eggs hatch in three to seven days and larvae immediately begin feeding on the roots of the plants. Feeding continues for three to four weeks before larvae pupate in the soil. A second generation of adults emerges in late June and lays third generation eggs. In northern locations where the growing season is short, this third generation may not complete development and will overwinter as pupae."
https://hort.uwex.edu/articles/cabbage-maggot/
Another location for this year's planting is best under the circumstances.
https://hort.uwex.edu/articles/cabbage-maggot/
Another location for this year's planting is best under the circumstances.
