Tiny, sometimes microscopic in size, plant-feeding spider mites can cause substantial damage to valuable ornamental trees and shrubs. Evergreens such as junipers and Colorado blue spruce become especially vulnerable to damage during times of hot, dry weather.
Spider mite damage can be best described as 'stippling' and gives trees a dusty/dirty appearance in the interior, followed by yellowing of foliage, browning and leaf drop
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 spider mites, as well as remove the dust that collects on foliage and interferes with their predators. Disruption of the webbing may also delay egg laying until new webbing is produced. Sometimes small changes, such as where plants are located or how they are watered, can greatly influence susceptibility to spider mite damage.