Tomato Borers

tomatoman(9B E Cen Fl)September 4, 2005

For the past few years, I have been plagued with a borer, that seems to attack about the time my tomatoes are getting ripe, sometimes just before and sometimes after harvesting the first batch. I've tried Neem oil, Volck oil, and low toxicity insecticides to no avail. The make a small hole usually near a crotch in the plant, and lay an egg, which hatches into a maggot, which morphs into a very small black borer looking insect. The plant starts wilting shortly after they start their dirty work of eating inside the stems, usually working towards the base of the stem.

Does anyone have any suggestions, or has anyone come up with an effective countermeasure? I'm at wits end, as they are winning.

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suze9(z8b Bastrop Co., TX)

The make a small hole usually near a crotch in the plant, and lay an egg, which hatches into a maggot, which morphs into a very small black borer looking insect.

Are you actually seeing the eggs that the moths have laid before they hatch, as well as the rest of the process you've just described? The way stalk borers work is that a moth lays the egg (usually in fall, and in weedy areas), then in spring, the egg hatches and the caterpillars (borers) eventually make their way to your tomato plants where they then proceed to bore into the stems and do damage.

Can you describe the 'insect' (color, length, width)? The stalk borers I'm aware of are caterpillars.

    Bookmark   September 4, 2005 at 11:28PM
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tomatoman(9B E Cen Fl)

Thank you for your reply. I have not seen an egg, but I have seen the maggot in various stages of development and it's a cream colored about .3 centimeter maggot, morphing into a cream colored looking .5 centimeter larva which becomes a small .4 centimeter, dark borer looking insect. I do not believe the maggot is capable of crawling up the plant, drilling a hole. Some times I have found as many as 6 larva in the declining plant. These tomatoes are planted in 10 gallon or larger pots, with no weeds

    Bookmark   September 5, 2005 at 12:18AM
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suze9(z8b Bastrop Co., TX)

I do not believe the maggot is capable of crawling up the plant, drilling a hole.

One wouldn't think so, but it seems like they are.

"The greatest injury is caused by late instar (stage) larvae. These larvae, half grown or larger, have migrated to cultivated plants from grasses and weeds. The larvae enter the stem by boring a hole, usually some distance above the ground. They bore in the stem, generally upwards, pushing frass and castings out the entrance or other holes made at intervals up the stem."
(I've attached the link below)

Your treatment options are somewhat limited. Bt is toxic to them if actually eaten, but the challenge is that they really don't eat anything on the outside of the plant before boring inward. I have heard of folks injecting Bt into sections of the stems that the borers seem to be in. Another thing you could try is to slice into the stem with a sharp razor blade in areas that the borers are in to get to them, then duct tape the sections tightly back together until they heal.

And of course, sevin would be toxic to them on contact. However, that would mean keeping your plants constantly coated in hopes that the borer would contact it on the way into the stem. From a practical perspective, I wouldn't recommend this though. Plus, I just don't care for the idea of constantly using sevin throughout an entire growing season like that.

If you think that the moths are actually laying the eggs on the plants (and again this doesn't jibe with what I've read), row cover would limit that quite a bit. However, my concern would be that in your climate, row cover would tend to hold too much heat in.

Here is a link that might be useful: stalk borer

    Bookmark   September 5, 2005 at 10:25PM
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tomatoman(9B E Cen Fl)

Your treatment options are somewhat limited. Bt is toxic to them if actually eaten, but the challenge is that they really don't eat anything on the outside of the plant before boring inward. I have heard of folks injecting Bt into sections of the stems that the borers seem to be in. Another thing you could try is to slice into the stem with a sharp razor blade in areas that the borers are in to get to them, then duct tape the sections tightly back together until they heal.

This sounds like an option I haven't explored, that is injecting BT into the holes. I have taken my borers into my local Ag office, but no one was able to identify them. I have seen fly maggots climb up the side of a 5 gal bucket, but these borer maggots would have to crawl quite a distance over low cut grass, then up about 18" of pot, across several inches of soil, then up the stem. Except for the 30 gal pots, they all have saucers too.

Last year I read about a new Cuban Pepper borer in S Fl, which also affects tomatoes, but I can't find that reference. The article offered no solution. This is very frustrating, because the only effective treatment would be a systemic toxin, which obviously I can't use. My control of insect pests has been limited to BT, Neem Oil, and a flashlight at night (LOL)

I thank you for responding and when my fall tomato crop starts maturing, I will monitor them closely and stand by with a syringe filled with BT, and possibly razor blades.

    Bookmark   September 6, 2005 at 12:42AM
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cmdrmcbragg

My tomatoes are becoming ripe and I have a problem of someting that is boring into the tomato. I have not seen anything yet just some of my tomatoes have holes in them. What could it be, and what can I do to stop it?

    Bookmark   June 27, 2006 at 10:34PM
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torquill(z9/sunset15 CA)

cmdrmcbragg, you'd do better to post a new thread for your question... but the short answer is tomato fruitworm, a.k.a. corn earworm. Bt (Bacillus thuriengensis, a bacteria you can buy) does help with those. If the holes are 1/8", round, and seem to go straight into the tomato, it might be pinworm, but my guess is that you have the more common fruitworm.

--Alison

    Bookmark   June 28, 2006 at 2:18AM
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