Zucchini plant: Is this a stem borer or other concerning disease? - Ask Extension
These marks are indentations in the stem of a zucchini plant. On the main stem, there seems also to be a fine slit penetrating the stem wall, but I c...
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Zucchini plant: Is this a stem borer or other concerning disease? #879182
Asked July 29, 2024, 9:16 AM EDT
These marks are indentations in the stem of a zucchini plant. On the main stem, there seems also to be a fine slit penetrating the stem wall, but I can't prove that without doing further damage. It also appears it might be plant material stuck to the stem, since scraping with fingernail reveals dark green material under the brown.
If this is a borer - worm of some kind - what can I do to keep it from killing the plant?
Lamoille County Vermont
Expert Response
Hello Ed, and thank you for contacting us at the UVM Extension Master Gardener Program. We appreciate you including the great photo to help us understand the situation.
How frustrating to find this possible damage on what looks to be an otherwise quite healthy zucchini plant.
If that is squash vine borer damage - caused by the larvae of the squash vine borer moth - you have noticed it at a very early stage, when any larvae would still be quite small. Are there any other signs that the plant is stressed, like wilted or discolored leaves? That would be a sign that immediate attention is required and the plant might or might not be salvageable.
The literature suggests that you could consider cutting into that large stem and scraping out any feeding larvae and their "frass" that you find, then covering the stem with moist dirt to encourage the formation of additional roots so that the plant could continue to grow and produce squash.
There is more information in these posts:
https://extension.umn.edu/yard-and-garden-insects/squash-vine-borers#physical-controls-3091762
https://www.thomas.k-state.edu/lawnandgarden/docs/squashbugs.pdf
Please let us know if you still have questions. I hope that you are able to keep that beautiful zucchini plant growing.
Best of luck with your gardening,
Michelle
How frustrating to find this possible damage on what looks to be an otherwise quite healthy zucchini plant.
If that is squash vine borer damage - caused by the larvae of the squash vine borer moth - you have noticed it at a very early stage, when any larvae would still be quite small. Are there any other signs that the plant is stressed, like wilted or discolored leaves? That would be a sign that immediate attention is required and the plant might or might not be salvageable.
The literature suggests that you could consider cutting into that large stem and scraping out any feeding larvae and their "frass" that you find, then covering the stem with moist dirt to encourage the formation of additional roots so that the plant could continue to grow and produce squash.
There is more information in these posts:
https://extension.umn.edu/yard-and-garden-insects/squash-vine-borers#physical-controls-3091762
https://www.thomas.k-state.edu/lawnandgarden/docs/squashbugs.pdf
Please let us know if you still have questions. I hope that you are able to keep that beautiful zucchini plant growing.
Best of luck with your gardening,
Michelle
