Pinworms on tomatoes

farmgardenerAugust 15, 2010

I know we have discussed this before, but HELP! I can get rid of the hornworms but not the pinworms. I've used BT, DE, Dipel, and Sevin - the pinworms keep coming.........they are ruining all my tomatoes and now getting into the okra. Advise please what worked for you?

I'm almost ready to pull the plants and forget the garden.

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I had good results with BT spray. There is another spray that seemed to kill a few. It was a Safer spray. At least I saw some dead ones after spraying with it. But the BT spray knocked them out. It takes more than one application. I will check the strength on the BT spray I used. If I'm not mixed up I think I saw 2 different concentrations and I bought the strongest one.But then again my memory might be playing tricks on me. Jay

    Bookmark   August 15, 2010 at 11:31PM
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Okiedawn OK Zone 7

Once they are in your tomatoes, there's nothing you can do about that generation, but since they can have up to 7 generations per year, you need to be spraying all your plants regularly with Bt 'kurstaki' which kills all caterpillers that ingest it.

Here's general info about controlling them.

The first step is to Google and find an image of the moth that lays the eggs. You need to learn to recognize it because then, when you see it arrive next year, you'll know it is time to start spraying your plants with Bt.

Secondly, the easy way to 'watch' for it is to go to some online supplier like Arbico Organics and buy a moth pheromone trap. When the pinworm moths start appearing in the trap, immediately begin a regular spray program with Bt.

Third, Google and find a photo of the tomato pinworm eggs. Once you have found the moths in your trap, start checking the backs of leaves for eggs. Remove and destroy any you find, but keep spraying with Bt to kill any that you don't find.

Fourth, learn to recognize leaf damage done by tomato pinworms in the 1st and 2nd instar. You'll see damage somewhat similar to leaf miner damage and then you'll see browning of the affected leaves. Always remove damaged leaves because the pinworms may still be living inside the leaves. Do not throw the leaves on the ground, the compost pile or over the fence. Put them in a trash bag and dispose of them immediately

Fifth, keep spraying all the leaves with Bt because you have to catch the pinworms while they are in the leaves or they'll get to your fruit and ruin it.

Sixth, when they've grown a little and reached the third instar, they attach themselves to the back of a leaf and weave a little web to hold the leaf folded shut. Always look for those leaves and remove and destroy them by putting them in the trash.

Once they reach the fruit, which is where they go after they emerge from the webbed leaf, so I think at that point they're in the fourth instar, they tunnel into the fruit and ruin it. They aren't done yet, though.

After they emerge from the fruit, they drop to the ground and go down into the soil. That is how they overwinter. So, this winter, after your garden is done for the year, hand-dig or rototill or plow your garden on a cold, cold day, going down at least two inches because that's how far underground they overwinter. By doing that, you'll expose the overwinter ones to cold weather which hopefully will freeze them. And, if you have poultry, it wouldn't hurt to turn them lose in the garden after you've tilled it so they can dig and scratch and destroy whatever pests they find.

It wouldn't hurt to turn over the soil multiple times several days apart, but be careful not to turn over the soil too deeply or you'll just bury them more want to expose them to cold temps that will kill them. If you turn over the ground several times over the course of the cold season, you'll kill more than if you just turn it over once.

Next spring, if you purchase plants instead of raising your own from seed, be sure to check the plants carefully for the leaf-miner type damage or brown spots on the leaves that indicate tomato pinworms and don't buy any plants that have those symptoms. Since pinworms are primarly a pest in greenhouses, it is common for a garden infestation to begin as an infested purchased plant. (Or, if a neighbor purchased an infested plant, they can migrate from that property to yours.)

There are some beneficial insects that might help, so do all you can to encourage beneficial insects. I see tomato pinworm damage on leaves occasionally and every now and then find one inside a folded leaf held together with webbing. I almost never (maybe once every 5 years) see damage on fruit, so that tells me that the beneficial insects in my garden are taking care of them before they reach the fruit, and I think it is likely that it is the parisitic moths that are killing them. (Even though I have Bt, I haven't sprayed it on tomato plants in years because I haven't needed to.) A healthy population of beneficial insects will keep minor pest invasions from becoming major ones.

I don't know if you use organic or chemical methods, so am not sure what else to suggest for control. Some people have found Bio-neem to be effective on them once they're in the leaf webs. There probably are chemical pesticides labeled for pinworms, but I can't advise you about them since I avoid chemicals as much as possible. However, most chemical pesticides harm beneficial insects, so if you use them, you can't count on having beneficial insects around to help you.

The most important thing is to learn their life cycle and be proactive and stop them from overwintering and establishing a permanent population. The second most important thing is to catch them when they're in the leaves.

For this year, it may be too late for most of your tomatoes and okra, but I bet if you check the foliage you'll find the webbing on a folded leaf that signals a tomato pinworm is in there. I saw one last week, removed it and smushed that sucker, leaf, web and all between my shoe and the ground.

They will move to various other plants, so pulling the plants won't necessary make them go away. They'll just move to something else.

Don't let them defeat you. There are very few pests for which there is not a workable control method, and pinworms are not one of the pests that cannot be controlled. However, you'll always have better luck controlling them early in the season and a much harder time late in the season.


Here is a link that might be useful: The Life Cycle of The Tomato Pinworm

    Bookmark   August 15, 2010 at 11:52PM
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