Hosts
Spruce spider mite is not an insect. It has eight legs and is thus considered an insect-relative. It feeds on pine, spruce and many other needled evergreens.
Spruce Spider Mite
Pathogen Type
Scientific Name
Oligonychus ununguis
Frequency
3
Severity
4
Symptoms
Thin silk strands may be found due to mite infestation. Stippling, tiny yellow to whitish spots due to feeding, may cause the needles to die and turn reddish brown when infestations are severe. Heavy infestations frequently cause the loss of entire branches or small trees.
Cycle
Spruce mites, feeding in the spring when temperatures are cool, tend to return in the fall in higher numbers. At first, young mites (larvae) have six legs but after one molt (nymphs) they have eight legs. The adult mites tend to be green, but can be brown. Spruce mites use the wind and their silk strands to disperse.
Management
Reduce stress on trees. Use a sheet of white paper to check for mites starting when saucer magnolia is in pink bud to early bloom. Shake or rap the spruce branch above the paper. If tiny green to brown, slow moving, "dust particles" are seen, a miticide may need to be applied. Spruce mites leave a green streak or blotch when crushed. Some insecticides tend to increase a mite problem by killing off the predatory mites. Insecticidal soap, summer spray oil, and chemical miticides are effective.
Credit
James E. Schuster, retired Extension Specialist, Horticulture & Plant Pathology and Dr. Philip L. Nixon, Extension Entomologist, Dept. of Crop Sciences, University of Illinois
PathogenID
67
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