Sheath mite on white pine
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EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team
Alerts. Check the label of any pesticide referenced to ensure your use is
included.
I had a
white pine sample come into my office this week where the needles were
yellow with brown tips and some needles had a blotched appearance.
Looking closer, I found Eriophyid mites feeding
at the base of the needles. The damage of this mite can mimic abiotic
problems, such as air pollution injury or drought, and needs to be taken
into consideration when diagnosing the problem.
To check if you are having a problem with these mites, you need to pull
the needles apart in order to see the mites. They are very small and you
will need a hand lens or microscope to see them. They are creamy white
and about 1/125 of an inch (0.2 mm) in length. Their bodies gradually
taper toward the end and somewhat shaped like a carrot. Most trees
usually support small populations that cause no visible damage. Flare
ups often occur on stressed trees or after applications of broad
spectrum insecticides that kill mite predators.
