Over the past few weeks several calls have been received asking about damage to Dwarf Alberta Spruce and Leyland Cypress, callers report white to yellow spotting, a greying of foliage or needles, webbing, and later a browning just before the foliage drops from the plant. The culprit, Spider Mites which have two spots on the upper side of their bodies a feature that is vital for proper identification. Mites are not insects, in fact they are arachnids, closely related to spiders and ticks. Often, spider mites are confused with small spiders due to having eight legs, two body regions and webbing being present on the plant. Spider mites will attack a wide variety of plants including fruits, vegetables, bedding plants, woody plants and shrubs, as well as evergreens.

Mites are most active during July and August due to thriving in hot dry conditions. Eggs are laid in vegetation where they overwinter until hatching when conditions are favorable. Juveniles and adults are very tiny and hard to see with the naked eye, the best technique to aid in identification is to place a white sheet of paper under the foliage give the plant several shakes and fold the paper. If mites are present there will be red streaks on the paper. The other tell -tale signs are the spotting of the foliage due to spider mites having piercing and sucking mouthparts, and the presence of webbing.

There are a couple of steps that can be taken to help prevent spider mite infestations. The most crucial step in prevention is to keep your plants watered, mites attack plants under stress. Mulch is also valuable in preventing attacks due to helping the plant conserve moisture. If mites are present, populations can be treated with insecticidal soaps and horticultural oils.  Insecticides are also available for more aggressive treatment with the active ingredient bifenthrin being the most widely used. For further information check out the N.C. Cooperative Extension website.