Systemic Insecticides for Spider Mites....?

runswithscissors(MT 4/5)February 8, 2014

The question about "to do or not to do" systemic insecticide has been raised on several threads on several different forums over the years. Good info but alot of variation of opinions. I'm raising the question to you guys, because, frankly, this just happens to be my favorite forum.

I've had great success growing things in my greenhouse over the winter, and I've always been a good houseplant person....but every single winter I am plagued with spider mites. (I know most people find these little buggers troublesome.) In the house I've gotten by with just spot spraying individual plants when they come down with them. It never gets rid of them, but controls them until summer when they all go outside and the mites seem to take a natural hiatus.

In the past I've used this method in my greenhouse, too, but most of my plants in the past have admittedly struggled anyway. Not so this year. When I set it up this past fall, alot....and I mean alot of spiders came in with me. (Yikes...I'm afraid of spiders) They have been helping keep the bug population...(even aphids and fungus gnats) under control. Except the mites. Man, the mites are an explosive epidemic this year. So I've been spot spraying individual plants, and it helps...but not much. I just broke down and ordered Avid. (Yeah, yeah...I know it's nasty stuff...but I consider myself smart enough to follow directions on the label so I'm not afraid to use it.) But before I do, I'm tossing around the idea of trying systemic insecticide to plant water first.

What is you-all's opinion on this stuff? It's going on ornamentals, and I do not intend to use it when it's nearing time to go outside, so that pollinating bees won't be affected by the pollen. And do you think all my spiders will croak if they eat things that have been poisoned by feeding on the poisoned plant? (I'm sure the Avid will kill them anyway.) It's kinda weird...I hate spiders, but they've sure been handy in the long as they don't hop on me and make me do the crazy-dance.

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SouthCountryGuy Zone 4b-5 SE BC(Zone 4b-5 SE BC Canada)

FWIW. I know people that raise caterpillars and I know from their experience that if the plant had ever been exposed to a systemic insecticide it usually kills the cats, even months later. What it will do to bees down the road I couldn't say and won't even speculate.

If you are at all concerned maybe you could try something like Safer's or a pyrethrum based spray. It may take more work but there won't be any lingering after affects.

I am not against pesticides either.


    Bookmark   February 8, 2014 at 8:37PM
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I would try it on a few plants and see if it works. Best to isolate those plants if you can so more mites can't just wander in. My guess is that it won't work though. Whenever I find mites on plants I immediately throw them out... not very helpful when you have a greenhouse full, I realize.

    Bookmark   February 9, 2014 at 1:04PM
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runswithscissors(MT 4/5)

Have been doing more research on this and my personal opinion, after reading many articles, is that the neonicotinoids (poison in the systemic pesticide) would have little if any impact on the bees in my yard. Here's why: the plants I'm using it on would be mainly used on my patio and in some flower beds. My pesticide-free yard however, is about 2 acres of wildflowers, flowering shrubs and trees. The few bees that will visit my patio instead of the rest of the yard would probably garnish very little pollen from my begonias and calibrochias by comparison.

SCG - it makes sense that the caterpillars die because they actually feed on the plant that has been treated. This tells me it stays in the plant tissue for quite awhile after treatment...which is good. It's hard to find a definitive answer as to whether the poison is in enough concentration in pollen to kill a bee. Certainly a few plants would not, although using it in entire fields may be harmful to a hive that collects alot of the pollen.

don - (smile) No, no isolating going on here:

    Bookmark   February 10, 2014 at 5:58PM
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have you thought about making your own nicotine spray first?
have you tried the buttermilk and flour spray on them,
this will suffocate large swaths of them with every treatment?

neonic's will become part of the bio-dynamic atmosphere

either way, i hope you can get the little beasts under submission

    Bookmark   February 11, 2014 at 1:05PM
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I use a product called SM 90, available from hydroponic stores. I needed something that was environmentally friendly and would kill pests and that's what they sold me. I've used it several times and it works. Just make sure you spray about 7 days apart to get everything.

    Bookmark   February 17, 2014 at 8:14AM
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runswithscissors(MT 4/5)

follow up-

Well it's been a few weeks since trying systemic insecticide and here's what I found:

It works wonders for scale, aphids, fungus gnats, and whiteflies. Those critters disappeared from my greenhouse in just a couple of weeks. Not so with spider-mites. It doesn't seem to affect spider-mites at all.
So I ended up spending boo-coo bucks on Avid and spot sprayed plants that were affected and it worked like a charm. For the first time it appears that my greenhouse is pest-free...(unfortunately, all the regular spiders have disappeared too, perhaps from lack of food.)

    Bookmark   March 5, 2014 at 5:31PM
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Neem oil, as a spray and soil treatment, will act as a systemic, with out putting yourself or the environment in jeopardy. It will not cause overnight destruction to pests, but rather acts as an antifeedant/deterant. Best used as a preventative, or in rotation with population knockdown measures.

Cold pressed is prime, as some heavily processed oils have the active ingredient Azadirachtin removed, and can be obtained at health food stores/natural pharmacies.

Spray water temperature and a good surfactant are important, to ensure proper emulsification and even spread. Warm water (70-80*F ideally) is important, as cold water will coagulate the oil, and hot water will reduce its impact.

For a soil drench to combat fungus gnats, root aphids, etc, 5-12ml per litre, mixed with an equal part surfactant (liquid soap, potassium based. Dr.Bonners preferably.)

For a spray, I use a 1% concentration with an equal part surfactant

Companion planting, trap crops, etc. There are many ways to control pests, a multi pronged approach is best.

SM90, with its nose tickling lemony bleach odour, is halfway between neem and Avid. Mainy comprised of canola and coriander oil. It does not work as a systemic, but is good to knock populations down, while rotating with insecticidal soaps and other control measures.

Dr.Bonners works wonders on its own, at 1% concentration. Peppermint brings the added benefit of peppermint oil, an insecticide in its own right, and Lavender will act as a deterant.

Ensure complete coverage of the plant, with particular focus on the underside of foliage. Spider mite eggs hatch every 3-5 days, an it is advisable to spray every 3-4 days until a measure of control is achieved.

As with bringing anything new into the garden, test a small plot or single plant at different concentrations, starting low, and observe results over 3-4 days.

    Bookmark   March 14, 2014 at 3:11PM
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