White Fly Counter Insurgency Tactics Query

My beautiful "frisbee" Hibiscus have become infested with white flies which are now damaging the leaves. One of the eight large hibiscus is doing well; it is the one I had to cut back due to trauma after transplanting. I wonder why these younger leaves are more resistant to the whiteflies? I have now applied a systemic granular treatment, Di Syston (sp?) recommended by our local nursery, but so far have seen no results except an offensive odor from the chemical. The flies are spreading meanwhile.

Now I am reading about Safer's Insecticide Soap, which is supposed to kill the flies and their larvae ... eventually. And Bayers, tree and shrub Insect Control, another systemic treatment but in liquid form applied to the area around the roots.

What works? Can I use both simultaneously? I understand that I'm trying to kill adult flies + larvae and the latter are on the underside of the leaves.

If you've already applied a systemic, I definitely wouldn't apply another systemic, the systemic stays in the plant and if you add more you'll overdose and that probably won't be good for the plant. The other thing to note about systemics is that they don't work instantly, they need to be absorbed through the roots and work their way through the plant's circulation until they get to the leaves, then if the bugs eat the leaves they'll die. But that process doesn't happen instantly. If you need to kill the ones that are there now, then a non-systemic regular sort of spray should be fine, just make sure that whiteflies are listed on the label as one of the things that the product kills (not all products work well on all pests).

The other thing that many people swear by for controlling whiteflies on hibiscus is using worm castings around the base of the plant, so if you have access to that it certainly wouldn't hurt either.

Worm castings work really well if you know the trick: They need to be absorbed by the roots. Dig a diagonal hole about 6-8 inches deep and pack it with the worm castings, then water thoroughly. It may take a week or 2 for the roots to take up enough to make the leaves very uninviting to whiteflies. In the meantime, use hort oil or hort soap to clean the leaves and coat the eggs. That should help reduce the infestation until the worm castings work.

May I say a word about di-syston, please? I so wish they would take this off the market! It has very high mammalian toxicity. In one example, two dogs died after the owners put it around a tree and then covered it up with soil and mulch. They let their two dogs (labs? - can't remember for sure, but large dogs) out to do their duty, and after they came back in the house, the owners left. When they returned later, both dogs were convulsing and died shortly thereafter. The necropsy pointed to di-syston. They can only presume that the dogs did their job there and got it on their paws, or perhaps they rolled in it. And they had covered it.. So you can see how toxic it is.....

I read some research a few years back that showed that using horicultural oil was more effective than any insecticide. The larvae tend to be underneath the leaves on the bottom portion of the plant. (You noticed that they didn't seem to be on new leaves.) Spray really good, making sure to get underneath the leaves. The research found that although the adults fly off when you start this, they return to the plant and get stuck in the oil.

After two weeks if dy-syston was going to work, wouldn't it have done the job by now?
I have sprayed on quite a bit of the Safer's Insecticide Soap, with no effect so far as I can tell.
I sprayed on the tops and bottoms of the leaves, as best I could.
Next, at one of your suggestions, I'm goint to try yellow fly trap paper--but I worry about this catching my wonderful gecko lizards who seem to love my hibiscus, despite (or because of?) the white flies.
Meanwhile the leaves are really showing the effects of these little monsters.

If I cut back these bushy flowers, will the new growth be more resistant? That appears to be the case in one of the plants, as I mentioned before.

Yes, if it was going to work I would think it should have worked in 2 weeks. I would really try the worm castings if I were you, there was a thread earlier this year on the Hibiscus forum where a number of people chimed in saying it had worked really well.

As far as cutting back--I don't know if that will help or not, my guess is if they don't have the older leaves anymore they'll quickly find the new growth. It is possible though that the new leaves took up the pesticide more effectively, but I don't think new growth is inherently any more resistant to whiteflies than older growth.

Whiteflies just seem to prefer the lower part of the plant to lay their eggs on. Don't know why. It's really not a matter of resistance.

What does the package say about how long it will take? It should be on there.

And I still maintain that horticultural oil is the best.

And now you pick......

The white flies have finally died off, or did they just move down the yard to the Myers Lemon tree?
In any case they are off the hibiscus, but I notice the plants that received all my attention (and chemicals) are looking a little brown and wilted on the ends. Shall I cut these back and let them grow back? That seemed to work on one of the plants that suffered from transplanting.
The smell from the di-Syston was horrible and my wife could not stand it. I won't use that again. I believe the Safer's Soap helped, but I had to reapply numerous times and almost apply it leaf by leaf.
I tried the sticky fly paper but found two dead lizards attached to them and did not like seeing that.

You should definitely consider worm castings next year--no nasty smell for your wife to put up with, and a lot less effort than the Safer's Soap (which could also make the leaves a bit crispy if you use too much).

As far as cutting back, your Hibiscus is the hardy variety that I think will die back in the winter anyway, so I don't there's really any point in cutting it back now unless looking at the brown parts of the leaves really bothers you. And if you have other plants that don't die back in the winter, now is not really the time of year that you want to stimulate new growth so I'd leave them alone too

I cut my 4x10 inch sticky traps in half the long way when I put them out.
It seems like the lizards don't get stuck to the skinnier pieces.
Then again maybe the lizards here are bigger than yours.
A lot of aligator lizards here.
Might be worth a try.
It also puts more traqs out-covers more area.
It doesn't seem to make any difference in the number of flies I catch.
I'm using safer brand.

The lizards we have are bright green anoles; they look like the one in those Geico commercials with a British accent. I can't bear to see them on my yellow sticky paper in the morning. They are small, about 4 inches at most.

I just read about another treatment: blasting with water http://www.hiddenvalleyhibiscus.com/care/pests.htm I think I will give that a try. This is a good site for hibiscus lover one of you put me on to above.

I'm in zone 8a, and the hibiscus are still producing new growth, but I agree now may not be the best time to prune.



This message was edited Sep 23, 2007 10:03 PM

I use Neem oil and Malathion mixed togather in a gallon of water.

I also vote for worm castings, has worked perfect for me, and feeds the soil which feeds the plant. Yay.

Please - explain to me how worm castings get rid of white flies. I really want to know.

I think there's something in them that the plant absorbs that makes it not taste good to the whiteflies.