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| What is an organic method to get rid of tomato hornworms? I understand that their larvas winter in the soil, and they will be back next year. Can I prevent that, without harsh chemicals? |
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| I walk around with a pair of scissors in my pocket. when I find one. bang I cut them either in half or with a good cut. they die quickly. Of course I always leave those with the white sacs on them alone. But I think BT can be used on them. I suspect that it might be easy to spot them at night with a flashlight. I have not tried that yet. Can someone confirm on that. I think they glow in the light and are easy to spot. I also suspect that they do most of their eating in the night. can someone confirm. |
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- Posted by tomatomike z7NC (My Page) on Mon, Nov 12, 07 at 12:18
| Tomato Hornworm pupae, not caterpillars, over winter in the ground and hatch out into moths that fly at night, mate and lay eggs in the late spring. There can be several generations a year depending on location. There is a forum on pests that might offer some insight into organic controls, but the Bt suggestion is about the only one aside from picking them off. The hornworms will feed almost constantly-day or night, but have a habit of feeding in the tops or at least outer branches of the plants which makes them easier to find. I don't know about the glow in the dark idea because I am on the lookout for the critters any time I am out in the garden. If you wait until dark to hunt them down, they're going to do alot of damage during daylight. |
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- Posted by blazepepper 7b, Auburn, GA (My Page) on Mon, Nov 12, 07 at 17:32
| Don't know if it is true, but I was told that if you plant cilantro plants near your tomatoes, that the horned worms won't touch them. give it a shot |
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| BT is the most commonly recommended, and is organic, control for hornworms. The worms eat the coated leaves and die. Buying parasitic wasps to control them also works. They are very tiny and are the ones responsible for the white pupae on the worm's backs (some call them eggs because that is what they look like). That's why you should never kill a worm that is carrying the white cases - let the wasps hatch. ;) As tomatomike said, the moth larvae overwinter in the soil and tilling will destroy some of them but no, you can't really prevent their return the following year because the moths can fly into your garden from anywhere. ;) Easiest and safest control is daily garden patrol with knife, scissors, or a can of soapy water and a pair of gloves and keep you eyes peeled for the moth eggs too. Good luck. ;) Dave |
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- Posted by naturegirl_2007 Michigan (My Page) on Mon, Nov 12, 07 at 20:34
| Watch for the pupa year round when you till and weed and destroy them. Watch for the telltale droppings(frass) and chewed leaves left by the larva during warm months and look nearby. After finding the first 20 this year the next couple of hundred were pretty easy to spot. If you don't have tons of plants, a daily trip down the rows can usually keep the hornworms under control with the simple pick and squish method. No other treatments are needed unless you have tons of plants or cannot look them over often. After seeing the damage they do, I have no trouble squishing them with my foot. Any of the pupa that show up in the soil while weeding or tilling get stomped on, also. Make sure they are on a hard spot on the ground and centered under your foot before squishing to avoid grossing yourself out. Then rub your foot around in the soil before lifting so you don't leave remains that gross out other garden visitors. Our local paper showed people removing hornworms from plants with kitchen tongs. Some of the little buggers can really grip the plants tightly. Might be a good tool for the squeamish. A friend of mine who can't stand to kill the larva throws them over the fence into the road. If they make it back the 75 feet to her garden she has to deal with them again. We definitely don't agree on how to dispose of them but sure do agree they have to get out of the garden. I gardened in two separate plots this year. One has never had hornworm problems but the new-this-year plot had lots. I'm hoping my vigilant control this past summer will reduce numbers for next year... but I'm also looking into companion plantings as part of the control. Hopefully, others will share success stories using various methods. |
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| I fork the soil where tomatoes grew to disturb the pupae (and hopefully kill them). Perhaps turning the soil brings the pupae to the soil surface and winter frosts kill them. I don't know. I started (hand) turning the soil after reading on some of the university sites that turning the soil can/will/may control the hornworm population. However, I never rototill. |
Here is a link that might be useful: Tomato hornworm + control of
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| The last 2 years I haven't seen a single hornworm. I did see a little HW damage on one plant this year but no hornworm. Maybe a bird ate it?? 3 years ago I found at least half a dozen. Some had the parasitic wasps imbedded in them, some didn't. They're very difficult to spot without the pupae, otherwise they blend in. I've never had significant damage from HW's and I don't till. The pic below is from 3 yrs ago. This is what happens to hornworms when you have a healthy population of parasitic wasps. The adult wasp inserts its eggs beneath the skin of the hornworm larva. The eggs hatch and the young braconids feed on the viscera of the hornworm until they pupate. This parasite is an important factor in control of hornworms and is most beneficial. There are many plants that attract parasitic wasps to your garden including the tiny white flowers on cilantro. See the link below.
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Here is a link that might be useful: Attracting parasitic wasps
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| I've never had problems with hw - I mean, I've had to pick a few off here and there - may be 6-8 in a bad year, squish them underfoot but that has got to be one of the gross-est thing I have seen... OMG! GROSS! Gardening is not for the squeamish, I guess. |
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- Posted by snowflake4 z7ok (My Page) on Tue, Nov 13, 07 at 12:03
| Thank you all for the advice. I used the manual removal this year, but I was grossed out all the time when I picked them up from the plant because of the gooey sensation they give you when you touch them. And they won’t let go of the plant! I read about BT before, but I wasn’t sure if it was acceptable in the organic gardening or not. Can BT be spread in the soil, to kill the pupas that winter there? If yes, do I do it now, in the fall, or wait until the spring? |
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- Posted by bmoser z6PA (b2m2@moserproduce.com) on Tue, Nov 13, 07 at 14:58
| Bt has to be on the foliage that the worm eats in order to be effective. Therefore the time of application is not just in the spring (becuase the residual life of Bt is relatively short) but either when hornworm populations are forecast or when you spot the first damage. I've learned that it is better to take immediate mass control steps rather than rely on hand picking hornworms off the plants. The responses in this thread are correct that the worms are usually easy to spot. That's because they reck havoc with the entire growing tip, including fruit, of the plant. Then there is the question of whether or not you picked the critter from all the damaged plants you see. While you are making observations and trying to tag the plants where you've harvested the critters 10 more plants are being devoured. The parasitic wasps usually become evident once your crop is in ruins. If you plan to purchase and release the wasps they likely will not stay around long without the hornworms- Sort of a Catch-22 situation. |
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| I recently heard that you shouldn't squash the tomato worms as they can release more larvae. Is this true? But a neighbor cuts them in half and then throws them out from the garden and the birds eat them. |
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| That is rubbish. The moth lays eggs which become caterpillars. If you squish them that's the end of it. Linda |
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| Horrible time with hornworms this year...usually not so bad but for some reason an over abundance this season. Pulled them off and fed them to the chickens. Even found one on one of my sweet banana pepper plants. I will definitely attempt to turn over the beds (with my son's help) and hopefully foil the dormant growth. Of course, killing over 30 of the buggers should reduce the population somewhat. Anyone else in zone 7b (Upstate SC) have a similar experience? |
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