All of the shrubs (and everything else) in my yard is full of swarming white flies. I don't remember having to deal with white flies this early in the growing season. After this frontal system moves through, the weather is going to be beautiful, so I have no excuse not to try to eradicate them.
Donna, I have successfully eliminated white flies on confederate rose and gardenias with a good layer of worm castings under the drip line. This would be an expensive proposition with an entire garden but perhaps you could try it with some of the more heavily infested shrubs. Repeated spraying of ultrafine oil should smother the eggs of the subsequent generations of the pesky flies. Since this is essentially vegetable oil, just like we use in the kitchen but in a form that disperses in fine droplets, it should not be overly harmful to beneficial insects like some of the chemical or neem based oils.
This is my fifth growing season here, and in the past I've done nothing to get rid of them because they didn't arrive until mid summer. When the heat index exceeds 100f, I refuse to go out and spray dozens of shrubs and citrus. (I just look forward to new growth the following spring - sad but true.) The large size of my yard renders organic treatments impractical, so I was going to go with a systemic spray that's supposed to last 3 mos. Since bees and butterflies don't feed on the foliage, I don't think it would harm them. How do you handle them?
Trouble is systemics go out through the flowers and citrus is host plant for monarch butterflies, they munch on the leaves. I understand how difficult it would be for you with a large garden. I hope someone comes up with a viable solution for you.
Been there, done that, donnacreation! First year I had my greenhouse, I thought it would be great to have fresh tomatoes in January, so I grew 3 plants inside. Worst decision of my life! Whitefly magnets! When I first discovered them (late November), I kind of blew it off as an "occupational hazard" of playing in a "real" GH, got out the Safer Soap and sprayed the bejeezes out of everything in the GH, thinking that was the end of it. Wrong. The next day they were still in evidence, so I sprayed everything again. To make a long and painful story short, NOTHING worked. Went through a succession of stuff---Horticultural oil, Neem oil, finally malathion (took them outside on a warm day to spray them). Nothing stopped them, and they were starting to appear on other plants in the GH. So I waited for a really cold night (below freezing---rare in Charleston). But I got lucky (in this case, and in this case only!--- and got the rare 30° degree night). Marched all 3 of those plants outside, put them on raised tables with a good northerly exposure, and said "die, suckers, die!" And they did! Next morning I batted one of those limpid tomato plants, and not ONE white fly appeared. Here's the key observation: I was able to eliminate the remaining population on the various other plants in the GH within a week with simple Safer Soap. The Tomato plants seemed to serve as the "mother host" plants for the entire GH! Got rid of them, and the problem became easily manageable with simple Safer Soap.
Roll forward 2 years. Noticed I had a growing whitefly problem in numerous backyard gardens. Thought back to my horrible gh experience with the tomatoes, and (frightened to death!) wondered if there was a "host" plant somewhere in these gardens that was fostering the evil white clouds. LSS, there was! It was a gardenia. Have no idea why those bugs chose that one plant as a "host" that year, but they did. I went around the various beds in the backyard tapping them with the wand of the sprayer. All had some whiteflies. But when I slapped that Gardenia, huge clouds of the things arose---so I'd found my host plant. I'm basically an organic grower. Always have been since age 12. But there's a time and a place for everything...I absolutely soaked that 7' gardenia with Merit. Lot of people think Merit is a systemic insecticide only, but the label claims otherwise; and my personal experience agrees with the label. It's also a pretty effective contact killer, too! Bottom line...2 weeks later, White flies were gone from the Gardenia, and all gardens. I wouldn't EAT those gardenia leaves, or make tea from them, but it doesn't have any whitefly problems, either. Neither do I... Bottom line learning for me here is that whiteflies seem to have a "favored" host plant. If you can find that plant and dispose of the problem there, you'll solve 99% of your problem. Just a non-scientific observation...
Stono, I think my original host may be a row of variegated chinese privet. It was awfully grungy until this spring's new growth, which is now white fly grand central. Ofcourse, my gardenias are also heavily infested. (I think I may have several host plants throughout my gardens.) How long does merit work? I'll be using Ardesia's suggestion, ultra fine oil, on my citrus. Thanks!
Lol and neighbors who think Sweet Autumn Clematis is pretty, even though it's eating everything in sight. SAC is nothing more then Kudzu with white flowers in my book.
After reading about donna's whitefly problem I ran outside to check my Confederate Rose and it was totally clean .. I did however find that my Abution hybridium in pots were infested and sprayed the bajeebers out of them.