Spider Mites on Jackson Hole’s Landscape Plants

After a mild winter and a relatively dry summer, we are experiencing greater pest outbreaks in the Jackson Hole area and throughout the Intermountain West.  One of the pests that we are seeing almost daily in Jackson Hole landscapes is the spider mite.

Spider Mite Damage on Tree Leaf

Spider mites are tiny 8 legged animals closely related to spiders. Several kinds are important pests of ornamental trees, shrubs and bedding plants. Under favorable conditions spider mites can build up rapidly and seriously threaten plant health.

Spider mites feed on plant leaves by piercing leaf tissues and sucking the green liquid that oozes out.  Leaves appear bronzed after the green color is lost from many tiny feeding spots. Heavily infested leaves and branches can become covered with an almost invisible webbing.

Spider Mites and Eggs on Leaf of Tree

Following severe infestations, leaves become discolored, producing an unthrifty gray or bronze look to the plant. Leaves and needles may ultimately become scorched and drop prematurely. Spider mites frequently kill plants or cause serious stress to them.
Adequate watering of plants during dry conditions can limit the importance of drought stress on spider mite outbreaks. Periodic hosing of plants with a forceful jet of water can physically remove and kill many mites, as well as remove the dust that collects on foliage and interferes with mite predators. Disruption of the webbing also may delay egg laying until new webbing is produced. Sometimes, small changes where mite-susceptible plants are located or how they are watered can greatly influence their susceptibility to spider mite damage.
Proper identification and the correct use of chemical controls is very important for the protection of your plants from mites.Spider mites are not insects.  As such, most chemical insecticides have no effect on the mite population.  To the contrary, insecticides reduce predatory insect populations that feed on the mites.  In many instances, a mite population (if present) rapidly increases after applying an insecticide.  Furthermore, strains of spider mites resistant to pesticides frequently develop, making control difficult. Because most miticides do not affect eggs, a repeat application at an approximately 10- to 14-day interval is usually needed for control.



Leave a Reply

Your email address will not be published. Required fields are marked *