Spider Mites are a summer pest. When the weather gets hot, that's the time to be on the lookout for spider mites, which damage rose foliage by sucking the cells dry.
How to identify mites? Foliage from above looks dry and when leaf is turned over you may see webbing. Spider mites attack the underside of the leaf and appear as tiny specks, like salt and pepper.
What causes mites? Water stressed plants, dust, use of chemical insecticides. Spider mites are not an insect - they are arachnoids - and use of insecticides kills off natural predators.
How to prevent? Besides good culture (lots of water, not using insecticides) a good plan of action during hot summer months is to remove bottom foliage (mites start from the ground up). Also hose off your plants at least once a week to help keep the foliage clean.
How to control? Spider mites reproduce at a rapid rate, so fast action is needed. An easy, effective and safe method is to use a water wand to wash the undersides of foliage. In case of infestations do this every day for a week to break the mites life cycle. Predatory insects such as green lacewings are helpful. If you need heavier artillery, there are miticides on the market. Always read the label and follow safety precautions.
For more info read UC IPM Guidelines on Spider Mites. And click here for Award of Merit article on Spider Mites from Marin Rose Society.
-Beverly Rose Hopper
Photo by Gail Trimble
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