whiteflies--what really works??

steve_in_los_ososJuly 17, 2010

I've been battling these pests for months now. I've tried spraying with insecticidal soap every other day for weeks.

I've tried Encarisa wasps. I've limited the number of plants which seem to host them (soon I won't be able to grow *any* tomatoes, basil, eggplants, peppers, cucumbers.....)

Nothing seems to work.


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We're fighting with them now in our GH....mostly on Toms and peppers. We tried some insecticidal soap with not much luck so we release dthe dogs of war. a few hundred lady beetles and about a half dozen yellow stick traps as well. We also clipped out quite a few infected tomato leaves. We're only a few days into this so I'll see how it goes. I still see the white flies and eggs but the beetles have only had a few days to work.

    Bookmark   July 19, 2010 at 3:30PM
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I released ladybugs earlier in the season for an outbreak of aphids (quite the "grand opening" year for my greenhouse....) and actually saw some munching of the green invaders, and some larval ladybugs produced, but they now all seem to be gone (aphids, however, have returned.....).

I don't think they ever molested the white flies or their immature offspring.

The trouble with soap is that it seems to encourage a black mold/fungus which I am now also battling.

Yipes! The first few months lulled me into a false sense of security. I'm wondering if I will now have to empty out the greenhouse, sterilize it, and let it sit empty for a month or two to beat this thing :-(

    Bookmark   July 20, 2010 at 12:25AM
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So far we've seen the lady beetles munching on the white flies eggs, but surprisingly many of the lady beetles we released seem to have dissapeared. We have screens in all of our vents so they could not have easily left the GH. We aren't finding them dead so I'm not sure where they went! The yellow sticky traps seem to be catching the adult whiteflies, and while we've caught many, there are still some that have avoided the traps so far.

We are finding the black/mold fungus on a few leaves but I was blaming it on the stick excretions from the whiteflies and not the soap spray so who knows. The whiteflies seem to only like the toms, peppers and a few other plants so I'm not sure what will happen once those plants are gone. Will they attack our other plants or move on...not really sure on that one.

Bugs really suck.

    Bookmark   July 22, 2010 at 9:46AM
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Belgianpup(Wa/Zone 7b)

Below is an interesting article on whitefly control by ATTRA.

The main controls seem to be yellow sticky cards, and specific varieties of ladybugs and parasitic wasps.

They recommend replacing the yellow sticky cards every other day with young crops, and using 2 cards per day per 1000sqft of greenhouse space for more mature crops. ('Crops' being a relative term, I'm sure.) They also say to place the traps at the same height as the tops of the plants.

Using a lot of yellow sticky traps can be expensive. A clever tip I read about years ago was to call around to local shops that change motor oil in cars, and ask if they use Pennzoil brand motor oil in the yellow plastic bottles. If you find a place, ask if you can have some their empty containers. When you get them home, drain out the dregs of motor oil and smear it on the outside of the bottles and use them as sticky traps. The whiteflies are attracted to the color and stick to the motor oil film. You can wipe the buggy surface with paper towels and refresh the oil.


Here is a link that might be useful: ATTRA: Whitefly control

    Bookmark   July 22, 2010 at 3:43PM
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There are several things you can use to successfully control whiteflies depending on your area. In my zone, they are a greenhouse pest and will not overwinter. In a southern zone they'll just keep reappearing in after treatment. One is a systemic but I'm not even going to mention it, because even though the active ingredient is now OTC in a reduced dosage, I suspect that won't control them, and it's been in use long enough now, I imagine resistance is built up, or soon shall be.

Like mentioned by Steve, it helps to clear out a g'house of every semblance of plant material, including weeds on the floor and scrubbing or power washing it, and then re-introducing only clean stock.

If your plant has sturdy leaves, like pepper, you can literally take soapy water and wash the eggs and instars off, but it isn't easy. The eggs are literally glued on. What works is oil. It works on all stages of whitefly from eggs to adult. I know peppers will tolerate an hort oil tx, because I have to treat my pepper crop each year when they are about halfway to sales date for aphids.......but I'm not so sure your tomatoes would without a lot of damage.

    Bookmark   July 22, 2010 at 4:30PM
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We're still continuing with the soap-spray, yellow-stick cards & lady beetle approach. It's helping but I suspect because of vacation we were a week or three behind in catching them initially so we're playing catch-up a little. We're finding more on our sticky cards and less on the plants so I think we're gaining on them.

We run our GH 12-months so emptying it out or freezing it out won't happen. We also have cats that spend a fair amount of time in the GH "grazing" so we'll never use a systemic or checmical insecticide eithwe. We are removing leaves that are simply covered in eggs and we're only seeing them on the toms, peppers and a few other plants so car. We'll keep fighting!

    Bookmark   July 23, 2010 at 11:04AM
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When I had greenhouses this is the method I used. Try it. Rip lightweight, rough plywood lengthwise into 7" width sections. Or, use any long pieces of lumber you might have stored. Paint with brilliant yellow paint. Figure out how to suspend these boards from GH roof and attach necessary hardware. Order on-line and brush on a coat of Tangletrap Insect Trap Coating, 1 qt. Brush-on Formula. This is organic, made by the TangleFoot Co. Suspend boards on chains over planting beds so that height of boards may be changed as needed. You have now created giant sticky traps which last a long time and the bottoms can be recoated over the trapped whiteflies as needed.

The next step is to attach an ostrich feather (available at craft stores) to a bamboo pole. In early morning and when in the GH brush the feather over whitefly infected plants, which always fly upward when disturbed and will be trapped. Takes a bit of time to set up but worth the effort.

    Bookmark   July 25, 2010 at 5:20PM
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Well...1000 ladybugs, and a dozen yelllow sticky traps later and the whiteflies are still winning. We just finally made a major move and pulled all of the produce out (they were fading anyway). The toms, potatoes, peppers, cukes, beans are all out now. We did find some residual whiteflies on our strawberries so we cut them back hard (we can;t remove the towers they are in) and we even removed the furry leafed pelargonium since the whieflies seemed to like those too. We're now monitoring the nearly empty GH, moving the affected plants far away and spraying the pelargonium (outside) with Dr. Earth insect spray. The battle rages on, but we have to solve it before we winterize our GH in a month or two or we're in big trouble. Hopefully the whiteflies that remain won't find a plant they like and we can kill the outside ones.

Why such a drastic move? Well we started to see black mildew/mold on a lot of plants so rather than lose everything we decided to move things outside for a week or two and see if that helps. Of course we'll not be bringing thr produce back in and we'll be monitoring everything else before bringing it back.


    Bookmark   August 24, 2010 at 11:27AM
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We've had som success with the Dr Earth fruit & veg insect spray, but it's taking multiple applications and we're still seeing a few whileflies.

We had a local farmer sugest Sevin, but we don't think it's safe for our kitties.

    Bookmark   August 26, 2010 at 10:35AM
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sandy0225(z5 Indiana)

Marathon granules. It will kill the whiteflies, but you won't be able to eat your produce. That doesn't sound like much of an issue now anyway with the shape they're in!
Get all the tomatoes and peppers etc out and use marathon on all the ornamentals. Start some new transplants of peppers and tomatoes and use the granules on them (it's approved for small transplant starting, just not final container growing). It's like $89.99 for a 5 lb gallon jug on ebay and it's going to last you forever if you use it according to directions. Store it in a basement or cool climate controlled place.
Once you have your greenhouse clean of them and it's cold outside, you won't have the problem. This time of year, even if you get your greenhouse clean of them, they'll be back from outside until a hard frost.
Also the black stuff is called sooty mold and it's caused by the sap of your plants that the whiteflies and aphids secrete. Not the insecticidal soap. After the problem is under control, you can wash it off the leaves and it won't come back. It's a symptom, not a cause.
If you get a fogger and fog insecticidal soap at night with the greenhouse closed up so that they can't escape, that will work too. Or use a total release spray like attain or x-clude, they are total release (fogger type) spray that you use when the greenhouse is all closed up. Then no animals etc are in there that you want when you spray it, not even you!
I was asking the same questions about whiteflies and aphids five years ago, so don't feel bad!

    Bookmark   August 27, 2010 at 7:57AM
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We have cats that are in the greenhouse all the time so we'd never use anything like marathon or sevin (the cats to occasionally graze on the plants) and we'd never use non-organic methods an anything we'd eat.

While we're not air-tight in our GH, we do have screens in all openings so hopefully we can keep them out.

    Bookmark   August 30, 2010 at 1:47PM
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