Spider mites are common garden pests that can infest fruit trees.
Spider mites are so named because they fall into the arachnid class, along with spiders and ticks. Plants often found in or around the home are common targets for these tiny mites, including fruit trees, vines and vegetable, berry and ornamental plants. There are many species of spider mites, including the Pacific spider mite and the strawberry spider mite, but identification is not particularly important for home treatments. They all require the same eradication or control methods. Does this Spark an idea?
Identifying a spider mite infestation is the first, most critical step in home treatment. Applying spider mite treatments if you have a different problem may make matters worse. One of the most apparent indications of spider mites is a stippling of white dots on infested leaves. Sometimes they will turn bronze in the earlier stages of damage; more severe damage will result in yellowing and dying leaves. The twigs, fruit and leaves may also be covered in small webs.
The University of California’s statewide Integrated Pest Management (IPM) program recommends placing a white sheet of paper under leaves displaying symptoms and then closely looking at what falls onto the sheet with a magnifying glass. Mites will move rapidly when disturbed. Also, check on the undersides of leaves for tiny white dots (possibly eggs) and moving mites.
Introduce Natural Enemies
One natural method of treatment is to introduce enemies of the spider mite that will not harm the plant. Predatory mites, including the western predatory mite and a mite species called Phytoseiulus, are effective treatments. These insects can usually be found at large gardening stores. These species feed on the mites themselves, not the leaves, clearing your infestation without harming your plants. Other options include the sixspotted thrip, the spider mite destroyer lady beetle, minute pirate bugs, bigeyed bugs and lacewings.
Control the Environment
Making your plants’ environment inhospitable to spider mites is a safe way to help control them. Dusty conditions lead to mite infestations, while wet conditions reduce populations. Keep your plants‘ soil moist and frequently spray the leaves with water until the infestation recedes. If the plants are outside, also spray down walkways, pathways and other areas surrounding the plants. Regularly and forcefully spraying the plant, particularly the undersides of the leaves, will noticeably reduce spider mite populations.
Insecticidal Sprays and Soaps
Insecticidal soaps and sprays can control spider mite infestations, but the wrong kinds will make the problem worse. The preferred treatment, as recommended by the University of California’s IPM program, is a petroleum-based horticultural oil or neem oil. Spraying regularly with the oils, as instructed on the package, can interrupt the neem’s life cycle, thus decreasing or eliminating populations. Soaps and oils should not be used on water-stressed plants or in weather above 90 degrees Fahrenheit, however. These products may also be toxic to certain plants, so be sure to read labels and test them on a single patch of the plant, waiting a few days to apply full treatment to monitor the plant’s reaction.
Do No Harm
Eliminating products or practices that aid spider mites in their growth or reproduction is essential to home treatments. Broad-spectrum insecticides should not be used, as they can eliminate the mite’s natural enemies or create conditions beneficial for their growth. For instance, using the insecticide carbaryl (Sevin) increased spider mite populations in lab experiments. Organophosphates and pyrethroids increase nitrogen production in leaves, on which the mites feed. Insecticides applied during hot weather, especially, can lead to mite outbreaks.
Water-stressed plants also suffer more damage from mite infestations, so be sure your plants have adequate water.