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By Tom Woods
Now is the time to check your tomato plants for tomato hornworms. These large caterpillars (up to 3-inches long) can quickly strip a tomato plant of most of if its leaves. This will not kill plants, but will definitely set them back.
The more leaves that are eaten, the longer it will take plants to recover. Tomato hornworms blend in well with tomato leaves and can be challenging to spot. Look for missing foliage and then search the stems for the caterpillars.
If you find them, either squish them (this is rather messy as they are large caterpillars), drown them in a bucket of soapy water, or spray the plants. Do not be afraid to handle the caterpillars; they do not bite or sting, despite the rather dangerous-looking horn.
Organic pesticides like B.t. (sold as Dipel and other brands) and Spinosad (sold as Captain Jack’s Dead Bug Brew and other brands) are both effective for caterpillar control. Spray late in the evening, as these products break down quickly in sunlight. Conventional pesticides include Sevin (carbaryl), permethrin and bifenthrin. Be sure to check the label for the pre-harvest interval, which is the number of days that you have to wait after spraying before harvesting.
These pests have come out early this year, in part due to the early hot weather. They hatch from eggs laid by a type of sphinx moth and will continue to be a problem all summer and into the fall, so you will have to keep scouting for these pests all season.
If you find caterpillars that appear to be covered in white, cigar-shaped cocoons, leave them in your garden. They have been parasitized by the braconid wasp, a very small beneficial wasp that does not sting people or harm plants. More beneficial wasps will hatch from the cocoons and infect other caterpillars, providing natural control for this pest.
Thanks to Charlotte Glen, horticulture agent in Pender County. Send your gardening questions or comments to: Brunswick County Master Gardener Column, P.O. Box 109, Bolivia, NC 28422, or call 253-2610. Enclose a self-addressed stamped envelope if requesting information or a reply. Answers may be printed in this column.