Spider mite SOS!!?

Dear Gardening Friends,


Does anyone among you know of a surefire method of getting rid of those most tenacious and dangerous of all pests, the spider mite? We have two 7 foot-high oleander on our terrace (we're in Switzerland, where the summers are hot; the plants spend the winter in a greenhouse), which we're trying to rid of spider mites once and for all. We've tried everything from horticultural soap to the most lethal insecticide. We're now reduced to hand-picking these creatures off each morning and evening - a procedure, which always yields about 10 mites per plant. My worries don't just concern the oleander, but also the lemon tree and callistemon, which both share the same sunny terrace side. How grateful I'll be for any and all suggestions you might have!


Thanks from a weary plant lover.

Spider mite SOS!!?
Your problem can be solved by getting Lady Bugs. You can order them off the Internet. They love to eat mites and you will not harm plants or other life by using chemicals.





Good luck.
Reply:dont care
Reply:I think you need a insecticide with the active ingredient Imidacloprid to get rid of Red Spider Mite.
Reply:Periodically check all plants for spider mites. Be especially vigilant during warm periods. And if you happen to take your plant outdoors, check it carefully before you bring it in. Isolate it from your other plants for a week or two, then check again. Spider mites abound in outside vegetation.





If you spot evidence of mites, isolate the plant immediately and bathe it weekly with mildly soapy water. Be sure to wash away any webbing and give the undersides of leaves a good scrubbing. This will remove all or most of the adults, but it won't affect the eggs. To get these, you have to wait a week until they hatch, then wash again. Repeat once more a week later.
Reply:Symptoms


A fine pale mottling develops on the upper leaf surface. In heavy infestations fine silk webbing can be seen on the plants, the leaves lose most of their green colour and dry up or fall off. Heavily infested plants are severely weakened and may die.





A very wide range of plants in glasshouses and homes can be attacked, and red spider will also cause problems in gardens in late summer, especially in hot dry summers. Large numbers of mites, up to 1mm long, and spherical eggs can be seen on the lower leaf surface (easier to see with a x10 hand lens).





Cause


Despite their name, during the spring and summer these sap-sucking mites are yellowish green with a pair of darker markings. They only become orange red during the autumn-winter resting period. Because of this they are sometimes called the glasshouse two-spotted mite.





Control


Glasshouse red spider mite can be difficult to control as it breeds rapidly in warm conditions and some strains of the mite have developed resistance to some insecticides. Biological control is an attractive alternative to using insecticides as it avoids resistance problems and the risk of spray damage to the plants.





Biological control


A predatory mite (Phytoseiulus persimilis) feeds on the eggs and active stages of glasshouse red spider mite. It needs good light and daytime temperatures of 21oC (70oF) or more on a regular basis if it is to breed faster than the pest. Its effective period of use is normally April to October.





As the predator is susceptible to insecticides, biological control cannot be used in conjunction with most chemical controls. The exceptions are those with very short persistence, such as plant oils or extracts (Vitax Organic 2 in 1 Pest and Disease Control, Growing Success Fruit %26amp; Veg Bug Killer) or fatty acids (Bayer Organic Pest Control, Doff Greenfly and Blackfly Killer, Fito Get Off Insect or Greenfingers Organic Pest Spray), which can be used to keep mite numbers down before it is time to introduce the predator.





Phytoseiulus and compatible biological controls for most other greenhouse pests can be obtained by mail order from specialist suppliers.





Chemical control


Insecticides containing bifenthrin (Bayer Sprayday Greenfly Killer Plus, Scotts Bug Clear or Doff All-In-One Garden Pest Killer) will control red spider mite, provided it has not gained resistance to this substance. Alternatives are sprays containing plant oils, plant extracts or fatty acids (see above). The latter pesticides may require more frequent applications.





Andrew Halstead