How to keep spider mites off your tomato plants – Orange County Register

Q: For several years I have had problems with spider mites on my tomato plants. I tried hosing down the plants in the morning but I think this caused blossom end rot on the tomatoes. I don’t want to spray anything that will harm the monarch butterflies. Should I give up tomatoes next year to see if that gets rid of spider mites?

A: Spider mites can be a major nuisance in dry climates. They will attack a wide variety of plants, including vegetables, ornamentals, grapevines, berries, and even houseplants. The presence of fine webs on leaves and petioles is the most obvious sign of an infestation. The mites themselves are barely visible without magnification, but they can be found on the undersides of the leaves. They can overwinter in mild climates, hiding in leaf litter or other sheltered places.

Once the weather warms, they begin to reproduce rapidly and can produce a new generation every week during the summer and early fall months.

They prefer dusty conditions, so flushing the foliage regularly with overhead watering is helpful. (Blossom end rot in tomatoes is caused by soil calcium deficiency and water stress, not overhead watering.) Spider mites also tend to appear on plants that are water stressed, so regular watering is essential.

Fortunately, there are many predators who will happily snack on spider mites. Ladybugs, six-spot thrips, pirate beetles, big-eyed beetles, lacewings, and some species of predatory mites all feed on spider mites. Avoid using broad spectrum insecticides as you don’t want to kill the predators. In fact, for this reason, spider mite infestations are at their worst immediately after pesticide treatment.

If the infestation is really severe, insecticidal oils or soaps can be used sparingly. Always follow label directions when using pesticides.

Q: I heard somewhere that you can overwinter pepper plants if you protect them from frost. Is that true?

A: Pepper plants are perennial in their native tropical climates. In fact, they can reach the size of a small tree. If you live where winter temperatures don’t get too low, you might be able to overwinter them.

Once they have finished producing, prune them back to about 18 inches and clear the bottom of fallen debris like dead leaves and old fruit. (You want the plant to survive the winter, not some hidden pests.) Cover with a frost blanket or use Wall O’ Water pesticides. When my kids were younger, we used a gallon or two of milk a day, so I just rinsed out the plastic jugs, filled them with water, and placed them around the plants. (We didn’t have money to buy frost blankets because we spent it on milk.)