Spider mites, over and over and over

[Jonathan Sachs]

I'm having severe problems with spider mites on three plum trees which I'm maintaining in pots until I have a place to put them in the ground. Nothing I have tried seems to help. Insecticidal soap kills the beasties off; but three or four days later, they're back. Then I spray them again, and the cycle repeats. With malathion, things are much the same.

Since the trees are not fruiting this year, I tried a systemic poison (disulfaton); after two months of application, it seems to have had no effect at all.

So far this year two of the three trees have been completely denuded of leaves, and have grown back a new set. Now they're losing the second set. I don't know how much more of this they can take.

I'm looking desperately for ideas on how to control this plague!

[Phisherman]

Spider mites become resistant quickly. Alternate Malathion, mitacide, and insecticidal soap every 4-5 days. Make sure you spray under the leaves. Your problem should get under control after 5 or 6 alternating treatments.

[Jonathan Sachs]

Thank you for the suggestions. I looked up "miticide" and found that there are several different varieties: methoprene, hydroprene, permethrin, probably others. What type would you advise me to look for?

[Amos Nomore]

I have found spider mites to be really difficult to control with any chemical agents. Phisherman's rotation will work, but you need to keep at it once you get started. You might throw neem in the regime. Spray the trees regularly with water to blow off webs and mites, and various residues. I have used Talstar One rotated with neem and insecticidal soap with fair success, but I no longer use pesticides in my garden, other than insecticidal soap and neem.

There are predatory mites available which take time to become established but, in the long run, will resolve the infestation.

I used predator mites to eliminate spider mites on Brugmansias indoors in the winter. There are numerous species which you can choose from, based on a variety of conditions. Good luck!

[Phisherman]

Just having three different types is what you want. Your local farmer's co-op may have a good product for mites. I have used "MiteX" by Bonide (a mix of cottonseed oil, cloves, and garlic), Malathion, and a home-made insecticidal soap (from Fels Naptha soap). All these can be safely used on food plants. Direct contact with the mites is required and a pressurized garden sprayer set to a fine mist is ideal. Use warm water to mix up your spray. Greenhouses are particularly subject to mass mite infestations. Use 5X magnifying glass 2-3 times a week looking under young leaves.

[Buderschnookie]

The best, most reliable, and most effective miticide is a mites natural predator like Phytoseiulus. Unfortunately you have wiped out all of your beneficial insects with your attempts to control the mites with chemicals.

If you could just bit the bullet for a bit and let your natural ecosystem recover I think you would have far less problems. Stop with the chemicals and systemics- they are doing no good and are preventing nature from dealing with things. Lay the pots on their sides and blast the foliage with water every other day or so and be done with it. You will have a brief overgrowth of spider mites but as nature comes back to life they will diminish to manageable numbers. A water blast is all you need to control them in the meantime.

I too used to use a different chemical for every "pest". But in 1996 I stopped cold turkey and after recovering my yard and plants have never been healthier. Beneficial insects returned and began controlling the pest species. Gardening is now fun and easy instead of smelly and toxic. Nature works.

[Jonathan Sachs]

I don't think the screened porch where these trees are kept has ever had much of a natural ecosystem. If I were able to plant them in the ground where trees belong, I'm sure the problem would go away. Until that is possible, I will have to compensate for the artificial environment with artificial pest controls.

[Jonathan Sachs]

I am trying that, so far with good results. I am alternating malathion with insecticidal soap and a neem oil product. I started with one application every three days, and I'm now stretching it to every four days.

Any thoughts on how long I need to continue this, and whether the application can safely be stretched any more? (Three days was about the length of time the trees stayed mite-free when I was using malathion alone.)

The trees have lost most of their second set of leaves, and are now sprouting the beginnings of a nice third set. Apparently they have some bounce in them yet.