Whiteflies have me on the verge ...

agardenstateof_mindJanuary 16, 2008

... of doing something really drastic.

I cleaned and fumigated the greenhouse this fall, and cleaned & treated all plants before placing them in there. Nevertheless, there they are again. Between last year and this, I've tried sticky traps, insecticidal soap, neem oil, di-syston systemic (Bonide) and cyfluthrin (Bayer), but they seem as abundant and as healthy as ever.

I'd really like to get this problem under control before I start my seeds.

Does anyone have any advice, anything that's worked for you ... short of nuking the whole greenhouse and its contents?

Thanks in advance,


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greenhouser(Middle TN Zone 6)

I'll trade you 20 white flies for 150,000 of my spider mites.

Have you tried those yellow No-Pest strips? I think I saw them at HD. In a closed GH they should work. But air it out a bit before you spend time in it. I can't get rid of spider mites in my Rion GH. I'm about to spray everything including the benches with both Neem oil and a Systemic yet again. My impatiens are spider magnets yet one of my favorite plants. I'd hate to give them up but it may come down to that.

    Bookmark   January 16, 2008 at 8:24PM
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ohiojay(z6 OH)

Without the correct, and quite expensive equipment, it is very difficult for us to get sprays to work effectively. We just cannot get the coverage beneath every leaf. Only those "fogger" type machines can assure this. One whitefly means 100,000 later! My neighbor works at a nursery down the road. This place is infested with whiteflies. Guess where she brings her veggy starter sets home from in the spring!! I battle them the rest of the summer/fall. They get on your clothes and next thing I know, they are in my greenhouse. I do believe world wars were started for less.

This spring/summer I sent away for some predator mites, out of desperation, from Sterling Insectary. I had spider mites covering my bananas in the greenhouse and outside as well. Shock of all shocks, they cleared them up. First time that beneficials have actually worked for me. Call them up and ask for Kim. Diane, I'm sure they have something that will help your whitefly problem. The website is pretty helpful. Just keep in mind that some beneficials require longer day periods to be effective.

All attempts using ladybugs and green lacewing eggs/larvae have resulted in wasted money/effort, and more stress/frustration.

    Bookmark   January 17, 2008 at 7:00AM
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sandy0225(z5 Indiana)

Have you tried Isotox spray? (acetaphate).It seemed to help my problem spots in the greenhouse, and it's got some systemic action. Ornamentals only.
But I think what you're doing is right, just rotate your sprays more, in other words use one that works via a different mode every few times. It sounds like maybe they are resistant to some of your chemicals or you're not getting good enough coverage with your spray, or check your measurements too. If you're using it too weak it won't be as effective and then you've exposed your bugs to it and they will be resistant. So throwing a properly mixed new spray in there with really good complete spray coverage might be just the ticket you're looking for.
I like to also keep a small hand sprayer loaded up with insecticidal soap and carry it with me in the greenhouse and blast any I see in between sprays. As far as I know, soap and horticultural oil are two things that bugs can't get resistant to, but the oil and soap might burn the leaves of your plants. Of course, it's not season yet anyway so that really wouldn't matter all that much. They would grow back.
You can also go out there with a vacuum cleaner and rustle the leaves and suck up the adults which puts a surprizing dent in the population too in between sprays.
It will eventually work, but it just won't be that instant fix you're looking for.
Whitefly predators might not be the answer right now. Most of them need 30-45 days for the chemical residues to wear off before you can put them out successfully. But be sure and check on that too because that would be the safest way.
Neem oil seems to be very popular on Gardenweb. But all it ever did for me was clog my sprayer. (I know there will be backlash for that!)
Sticky cards are really just for monitoring, and they won't take out a population by themselves.

Here is a link that might be useful: spray rotation guidelines

    Bookmark   January 17, 2008 at 7:39AM
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watergal(z6/7 Westminster, MD)

I swear by products with Imidacloprid in them. I used Marathon granules to clear up a terrible infestation on hibiscus in my grow room last winter. It's a systemic that lasts for many months. Because it's a granule, you don't have to deal with messy sprays, or worry about missing a few leaves. It does take a while to work its way up into larger or woody plants, but it will get there eventually. It is expensive - about $135 for a 5 gallon jug that should last you quite a while. And hard to find - you will need to go to a horticultural supply place that caters to professional growers. I can give you a link to one online if you need it.

You can also spray or drench with an imidacloprid product. Bayer makes several that are easy to find - Rose & Flower Spray, 3 in 1, Tree and Shrub drench, there are some newer ones - check the Bayer website for details. One of the sprays even includes a miticide. Most of them are not labelled for indoor use though. Check the label to be sure.

The one caveat with the granules, especially in a greenhouse setting, is that you must not water to the point of draining out the bottom for the first 10 days or three waterings after you apply it (that's from my faulty memory - I think it's correct, but check the label to be sure).

I don't think you can use it on edibles.

    Bookmark   January 17, 2008 at 7:48AM
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Thank you all for your suggestions. I'll follow up on these. I do have the Imidacloprid in the Bayer rose product, but it isn't labeled for use in container-grown plants. Excellent point, Sandy, about waiting a while before introducing beneficials.

I'm afraid the datura in there seem to be their favorite ... so much so that I'm tempted to just get rid of the plants, but the infernal bugs would just relocate to the remaining plants; and those datura are so pretty in bloom - double, pale yellow flowers.

Sure hope I can get the problem under control before spring, when they'll move outside to the vegetable garden like they did last year. With a koi pond in the back yard, I have more control options in the greenhouse than I have outdoors, where spray drift could be a serious problem. Ohiojay, thank you for the beneficial source recommendation - that might be my best option for summer control. (Any beneficials that "drift" into the koi pond would simply become food.)


    Bookmark   January 17, 2008 at 3:38PM
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ohiojay(z6 OH)

Sandy, Neem was clogging my sprayer as well. I started using a bit of cheesecloth to filter the particles out before adding to my sprayer. So far so good.

    Bookmark   January 17, 2008 at 8:23PM
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ponderosaq(Z7 VA)

If it makes you feel any better you aren't alone I have had this problem for years too. I rotate sprays of all types, use sheets of yellow card with tangletrap on them every day, use systemic granules and still can't win. I've even used professional GH bombs. I think these critters are just resistant to everything.......But I'll keep on battling!


    Bookmark   January 19, 2008 at 6:32PM
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