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Posted by Leafhead none (My Page) on
Thu, Apr 4, 13 at 13:28

what is the best pesticide for Whitefly in a populated greenhouse? I want to choose a remedy that is safe for the elderly.

Follow-Up Postings:

RE: Whitefly

better water management???

i dont understand what you mean by a populated greenhouse.. and why elderly live in it??? .. more clarity please ....

is there no ability to close it off for a few days for treatment???

and it might matter where you are ... can the plants be removed outdoors .. treated outdoors.. the house sterilized down by cleaning.. and the plants returned????

and how sure are you .. on the ID???? .. are you guessing.. or are you sure ..????


RE: Whitefly

A little background...
It is a shared greenhouse at an assisted living facility where the residents garden and gather for meditation together.
Oh, and I'm sure it's whitefly.
It all started c an infested Shefflera arboracola....
Now it's on one of its faves, Hibiscus.
There is still a little snow on the ground here in Wisconsin. I guess we could close it off. What would you use and what do you think of a systemic?

RE: Whitefly

Any pesticide you spray in that greenhouse will also kill off any beneficials, or predators of whitefly, that may be there and may well cause respiratory problems in anyone working on that greenhouse. Most often the whitefly population grows after pesticides are sprayed because the predators have been killed off.
Yellow Sticky traps can be placed to help trap the adults and Insecticidal Soaps can be sprayed to aid in controlling the nymphs and quite often giving the affected plants a good shower can help by washing off both the nymphs and eggs.
Perhaps this from the University of California might be of some interest.

Here is a link that might be useful: About Whiteflies

RE: Whitefly

Nymphs cannot readily be rinsed off with water. Neem oil is a very good option and one that has very little effect on non target insects. It, as well as insecticidal soapy, are mentioned as options in the link that kimmsr attached. These need to be directed to the underside of the foliage. The neem can smother the non mobile nymphs and eggs and due to its unique anti-feedant qualities.

There really aren't any systemic insecticides recommended for the control of whitefly. Their use can result in a huge increase of those other greenhouse pests....scale and spider mites.

RE: Whitefly

Yikes!! I was really shying away from caustic chems anyway...
Got a new idea;) Green Lacewing larvae, after a vigorous hosing off c Neem oil and/or Safer Soap.
I found a source for larvae for sale online. They're hungry, they're native and they're inexpensive.
And best of all, they're harmless and will make a great education opportunity for the Residents.
And they'll control those other pests, too:)
Thanx for the info and link. You both gave me some great ideas and a safe battle plan.

RE: Whitefly

Leafhead.....use just the insecticidal soap for this job. It's a good idea to try to get a grip on the population but you don't want to apply anything that might prevent the lacewings from feeding on the whitefly.

Be certain that the plants have had a chance to dry before putting the lacewing out. Are you buying the critters from a reputable source? Just asking because you want them to be healthy and hungry when they arrive.

RE: Whitefly

If just the soap is enough to do the job, I won't bother c the lacewing. I can always use them as a second line of defense if they start coming back.
I've been shopping around for the best deals; does anyone know how to assure good quality thru the mail?

RE: Whitefly

I'm looking for a reasonable lacewing vendor also. And what's the most economical/reliable way to purchase them?

Eggs? eggs on cards? adults?

My county ext. gave me this address. Ladybugs are pretty easy -- buy and release.. But I'm new to the lacewing release. I just don't want to go through the same thing as I have with ladybugs--- PAY, release only to see them gone 2 weeks later and then in august shake my tomato and pepper plants to see them loaded with whitefly. :(



RE: Whitefly

I just typed in "lacewing larvae" and got several sources.The easiest way to buy them is while they are still larvae.
They also have parasitic flies, but they are very tiny.

RE: Whitefly

The lacewing larvae are also very tiny.

I don't think for one second that insecticidal soaps will get rid of the whitefly problem in this greenhouse. We need to emphasize that whiteflies are one of the most persistant of all plant pests and dreaded in a greenhouse.

All you can expect from the soaps is some knock-down of the flitting adults.....maybe some nymph kill if you concentrate on getting the spray underneath the foliage.

I don't really have a lot of confidence in the use of lacewing larvae, either. How many do you plan to release? You will probably see a reduction in numbers with the use of both methods, but don't expect to eliminate them.

I think that what I would do is apply a cold pressed neem extract on the underside of the foliage. An occasional light spray of a soap solution can kill some adults. You will have to repeat applications periodically as long as there are plants in the greenhouse. They are the gift that keeps on giving.

Neem extract has a strange odor and the patrons need to be warned about that. It will dissipate in a couple of days. You will also have to be mindful of temperature cannot spray soaps or oils on hot, sunny days. The plants should be watered well the day before. Patrons can enter the greenhouse as soon as the application has dried. There are zero problems from inhalation or contact, however.

By the way....neem extract is very effective at controlling spider mites and certain plant diseases, too.

RE: Whitefly

A gardener should never spray anything on a plant in full sun or on a hot day and most every label for spray products I have seen states that clearly.
Neem Oil products and Insecticidal Soaps are both broad spectrum poisons that can kill beneficial insects as well as the insect pests if not used carefully. Most every knowledgeable source I have read says if poisons are to be used in the garden to spray at times when the beneficial insects are not around, very early in the morning or late in the evening.

RE: Whitefly

Perfect. We have several rainy/cloudy days ahead...
I can attack c Neem first, wait a few days and come in c the second wave, the Lacewing Larvae.
I'm choosing Neem because I feel it is the least toxic of my options, according to this forum. It seems safe around people.
I HATE spraying anything, but since this is a relatively new infestation, I hope to get ahead of it before it gets out of my control. (My job starts Tuesday).
I'll be spraying in the early AM to avoid damage to plants and beneficial insects alike.

RE: Whitefly

Leafhead, seems like a worthwhile plan to me!

RE: Whitefly

Hang some whitefly strips around the g reenhouse. You'll be amazed at how many will be stuck to them! Hundreds. Get them at a garden center. I put them all around my plants. Easy and no poison.

RE: Whitefly

Sounds good, too...I'll be ready to try anything non-toxic and effective.
I have not yet completed my Corporate Orientation for this job (this coming Tuesday) and I expect to walk into a shinola-storm of Whitefly...
Wish me luck; I'll need all the help I can get =/

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