I was repotting and fussing with the pricklies today and squished two critters I believe to be red spider mites (almost invisible, tomato-red, move pretty quick but not quick enough!).
None of the plants show obvious signs of infestation but I'd rather nip this in the bud, so to speak, because it'll be several weeks before I can open up the sun porch and let fresh air in. (This is Maine, it ain't summer 'til the pool thaws.)
Before I go buy something that's going to give me worse problems than I already have, any suggestions for a good way to get rid of spider mites? I have a mixed collection (various cactus, some other succulents) in 3-6 inch clay pots.
Red Spider Mites - best pesticide?
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Rebel Squirrel
- Posts: 111
- Joined: Mon Jul 24, 2006 10:26 pm
- Location: Maine, USA
Mites are hard to control. I do have two kinds of pesticide, including the insecticide that contains imidacloprid, a systemic, but neither one of them claims, that it is effective against mites. You may have to purchase a miticide, which is a pesticide formulated specifically for mites. There may also be other ways of dealing with this kind of problem, but I would not know whether or not they are effective. I would first go ahead and closely examine the cacti for mite presence. Spidermites do produce thin, spiderlike webbing and that should be visible quite well when you use a magnifying glass. Also, they would be seemingly suspended in mid-air above the plant surface and maybe scurry toward the areoles (spines) when sensing danger. Another thing to know: most of the time plant feeding pests are not very fast moving, while predators are. There are some kinds of predatory mites around that also might be red colored. However, those might feed on other mites and only be an indicator of a problem that is affecting the plant. I understand, that because of their small size it is very difficult to get a good look at this specific pest and/or to photograph it for identification purposes. However, if you are dealing with plant parasitic mites, you should be doing something as quickly as possible, because they can be rather destructive and multiply very quickly.
Harald
Harald
There is no best insecticide for these. They may be resistant to any single insecticide and you should always be prepared to use a different one if you get poor results. Always try to use a different one than you used last time. I won't even mention specifics, there are quite a number of different ones, just pick a bottle that has spider mites on the label. In all cases, you should spray at least twice ten days apart, and probably three or four times. Insecticides may not kill all the eggs and these will hatch out after a week or so.
You may also wish to try non-poison controls, such as soaps, oils, alcohols, or just plain water. Mites cannot become resistant to these but the very physical action which kills the mites can also damage plants (except the water) so they are a little more tricky. Try them first on plants you can afford to lose until you get the dose correct, absolutely avoid sunlight or very high temperatures after you spray. Some plants like Echeverias you will probably never be able to do this. Water sprays at any time will discourage mites by reducing their growth rates and encouraging a fungal parasite that is the main predator of many mites.
Do not use Imidacloprid on them, it will at best do nothing, cost you money, and encourage resistance in other pests. At worst, it can cause mite population explosions by killing natural predators and by increasing the fertility of the mites.
There are also biological controls, predatory mites that you can buy and release in the greenhouse to eat the bad guys. Typically these are chosen to breed faster than the spider mites under greenhouse conditions and can be extremely effective for a whole season and possibly longer. It is almost impossible to prevent mite outbreaks using pesticides, and usually you don't spot them until there has been quite a bit of damage, but mite predators do a good job of continuous control until they die out.
Most greenhouses come complete with predatory mites of some sort, and most of the time they will prevent outbreaks, so don't just spray miticides about for the fun of it. Make sure you have live spider mites on your plants, then spray until they are dead. Examine all neighbouring plants also, you will soon learn which types are susceptible.
You may also wish to try non-poison controls, such as soaps, oils, alcohols, or just plain water. Mites cannot become resistant to these but the very physical action which kills the mites can also damage plants (except the water) so they are a little more tricky. Try them first on plants you can afford to lose until you get the dose correct, absolutely avoid sunlight or very high temperatures after you spray. Some plants like Echeverias you will probably never be able to do this. Water sprays at any time will discourage mites by reducing their growth rates and encouraging a fungal parasite that is the main predator of many mites.
Do not use Imidacloprid on them, it will at best do nothing, cost you money, and encourage resistance in other pests. At worst, it can cause mite population explosions by killing natural predators and by increasing the fertility of the mites.
There are also biological controls, predatory mites that you can buy and release in the greenhouse to eat the bad guys. Typically these are chosen to breed faster than the spider mites under greenhouse conditions and can be extremely effective for a whole season and possibly longer. It is almost impossible to prevent mite outbreaks using pesticides, and usually you don't spot them until there has been quite a bit of damage, but mite predators do a good job of continuous control until they die out.
Most greenhouses come complete with predatory mites of some sort, and most of the time they will prevent outbreaks, so don't just spray miticides about for the fun of it. Make sure you have live spider mites on your plants, then spray until they are dead. Examine all neighbouring plants also, you will soon learn which types are susceptible.
--ian