In the Garden:
Inland Northwest, High Desert
Mite damage on spruces has been severe this summer.
Those Dusty Spider Mites
Remember when you were little and you put your thumb over the end of the hose and sprayed everything in sight? Bet you didn't know you were training to become a great spider mite killer someday. Hot, dry weather and dusty, dry leaves are just the ticket for spider mites. Keeping plants cool and wet discourages these critters. Right now, in the hottest, driest part of summer, is exactly when we should be spraying water.
Prevention Is Key
Spider mite populations can explode quickly, and it's hard to see the actual mites themselves, so watch for telltale signs of their activity such as tiny webbing and dull, mottled looking leaves or needles. Mites attack a broad range of plants - I'm finding them on the evergreens a lot this hot, dry summer.
Hose Them Down
The very best miticide is a good hosing down. Attach a nozzle to the end of the hose. Use one that will squirt a hard stream all the way up a tree. Since spider mites can be all over leaves, it's been my practice to cover every branch and twig of my ornamentals with a hard spray of water. Some of the little monsters are crushed by the force of the water, and the others just go away. During the hot summer months I try to play in the water, er, wash all the plant leaves about once a week. If spider mites don't get a foothold, they'll never be a problem.
Spray Them Early
Trees can be sprayed anytime, but shrubs that are susceptible to diseases, such as roses, should be sprayed early in the day. That allows the water to dry before the cool of evening, when fungal diseases thrive.
Soap Them Away
If you still have mites after all this spraying, try mixing some insecticidal soap with the water to kill the pests. Mites can't stand soap, and your leaves and needles will be less dusty too.
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