I only have a couple of things that get bothered by whiteflies...Blue Dawn morning glory and my Rose of Sharon. Fortunately that's not much to have to deal with. I use about an inch deep mulch of worm castings around the base of each and that got rid of the whiteflies. This was maybe 4-5 years ago and they've not come back.

Jeepers. I have an entire chain link fence covered in blue morning glories. I'll have to go down and shake them to see. Right now, it looks to only be one of my hydrangeas, oddly. And really badly invested. The plant looks okay right now, but I have to get a handle on it. I do have some worm castings that I can spread underneath. I'll try that, thanks gypsy.

Patty S.

I've not had whiteflies bother my hydrangeas...... so far.

Hah, I said, "invested", meant "infested"! And I thought it was rather odd they attacked just this one hydrangea. I may spray it with either insecticidal soap or Neem oil tomorrow, as well as the ground around it. Haven't found them on anything else, but I'm going to check all my hibiscus. I think I have them down on my blueberries in the lower yard, which is really awful, since they are starting to ripen!

Patty S.

The problem with white flies is the eggs hatch in the soil. Therefore if you fail to treat them as the new eggs hatch, you get them again. Even a short time of failing to treat them could mean disaster. I think the eggs can hatch in a week, and also it is hard to get the underside of leaves. Once you got them, you got them forever, unless you ripe out all the plants and then sterilize the soil, and then of course they will come back again from else where.

I will be spraying the soil with Neem, but I doubt that will do anything to the eggs I'm thinking. I may need to resort to multiple applications of imidicloprid, which I really can only do on my ornamentals, not my edibles. My blueberries down in the lower yard are all affected, which I'm really upset about. So, we'll have to see. I may send a message to the Master Gardeners in my area to see what they suggest. Hopefully, Vince Lazaneo will respond. I really respect his opinions. And how on earth do you "sterilize" soil??

Patty S.

I used the worm castings on my canna lilies and they never returned. May be hocus pocus, and I just got lucky. I don't know if any studies have been done on it. I cut the affected plants back as far as possible and scooped up the surface soil, threw down the worm castings, and that was it. I tore out my hibiscus, though- it was a breeding ground for them.
Renee

You can't sterile the soil. You would have to dig it all up and bake it in a oven. They say you can put plastic on top to solarize the soil. I have never done this, but you can look it up. You would of to remove all the plant and of course the white flies would come back anyway. I was merely pointing out the futility.

I know, tropical :-) I'm joshing you. It's impossible first off, and even if you could, you'd then ruin all the biodiversity in the soil by killing all the good microbes, earthworms, etc. "Solarizing" soil is a certain way to give you dead soil. Not recommended. So far, I've been able to get the population down to a low roar, and will continue spraying the hydrangea and the blueberries repeatedly. Oddly, not one of my many, many hibiscus are infested. I would be sick if they get infested, as they become host plants and perpetuate the problem. I'd have to yank them all out. I have several very lovely specimens and that would be heartbreaking.

Patty S.

Don't yank out. You can find something out there that will do the job. Sometimes white flies are immune to one thing, try another. You need to treat weekly, don't just let the eggs go to hatch. Even when it rains for a week, the eggs will still hatch like clockwork. In fact rain speeds up the process of new aphids coming out and aphids clone themselves in five days.

I will, tropical. I have some very unique cultivars, one I just am in love with which you can't even find anymore. I live pretty close to Hidden Valley Hibiscus in Oceanside, who are renowned hibiscus propagators, and many of the big fancy hibiscus we enjoy have come from their breeding program. I'll just have to keep an eye on all of them to make sure they don't get infested. I probably have over 30 hibiscus on my property, maybe more.

Patty S.

Always check under the leaves near the bottom, often one sprays the plant and it looks ok, so you move on. Then if you go and check under the lower leaves that is where the bad insect eggs are hiding. I can't grow Hibiscus at all, what a shame. It's not hot enough here.

Imidicloprid? The same type of neocontinoid just implicated in bee deaths across the nation? I stick to K-based insecticidal soaps for whiteflies, but I do have to douse the underside of the leaves, which is annoying in practice. Lacewings are a gardeners friend here too.

Here is a link that might be useful: UC IPM whiteflies

Nope. Imidicloprid is not quite in the same category as some of the other neoconitnoids. I only use it on things that are NOT blooming. And, as a last measure, as there are good research that shows it can cause other issues, like increasing spider mite activity. So, only in rare instances. I have too much at stake in my yard not to be aggressive with whitefly. And, I've ONLY applied it to ONE plant in my acre plus yard.

Patty S.

Nope. Imidicloprid is not quite in the same category as some of the other neoconitnoids. I only use it on things that are NOT blooming. And, as a last measure, as there are good research that shows it can cause other issues, like increasing spider mite activity. So, only in rare instances. I have too much at stake in my yard not to be aggressive with whitefly. And, I've ONLY applied it to ONE plant in my acre plus yard.

Patty S.

Hoosierquilt,i live in Oceanside and i've never heard of hidden valley hibiscus!! Guess i'll have to look that one up.We have several different hibiscus,but they all came from andersons,or armstrongs or the big box stores.Guess i don't get out enough.LOL,LOL
Kathi

Hidden Valley Hibiscus is WAY out there, in the hills up near Camp Pendleton. But, I think they're moving, so they won't be having any Open Houses this year. And, many of the hibiscus you may have bought could have either been developed or grown by Hidden Valley, especially if they're very fancy.

Patty S.

I'm in Vista, too, Patty, and so far we don't have whiteflies in my garden (tho now I need to go outside and check). I had great success in my previous Encinitas garden spraying the undersides of the leaves with water every couple of days (after first removing the leaves that were covered in that nasty white hanging mess they make). Have heard worm castings are also good, but if you have a lot of plants that are affected that can be pretty pricy. A gal used to sell castings at the Vista Farmers Market, but I haven't been there in months so I don't know if she's still there.

Also, you can look on the underside of the leaves and see their spiral pattern of white eggs - just rub your gloved finger on them to remove them. Good luck!!!

Here is a link that might be useful: San Diego Horticultural Society

Hi Susi! It's Patty Sliney :-) I'm going to put down more worm castings under the plants I've seen with Whiteflies - the blueberries and the one hydrangea, and now a couple of fuschias. And that's where I get my worm castings from, too - the gal at the Vista Farmer's Market. I wonder if she's not coming anymore? She used to do a pretty brisk business there. So far, they're declined, so hopefully some of my more organic approaches have worked, but if I have to, I'm resorting to imidicloprid. I hate to do that, but I have SO many hibiscus, and the thought of having to remove them if they end up becoming a host plant is just too sad to think about. For those that don't know Susi, she was our long standing, esteemed San Diego Hort Society President and current board member. We have one of the best hort society organizations in the country, and I feel very fortunate to be a member :-)

Patty S.

Hi Patty - I was pretty sure that was you. ;-) Before you resort to chemical solutions, do try spraying the underside of the leave with water from your hose and also removing the spiral of eggs from below the leaves. If you spray every couple of days you could see a big improvement rapidly like I did. Your garden sounds lovely. Thanks for the pats on my back.

I'll try another spraying of insecticidal soap, then. That's what I used the first time around. Tricky to get underneath the leaves without spraying yourself in the face :-) And thank you, I owe you a tour of my garden!

Patty S.