Publication 444-241, August 1996
PLANTS ATTACKED:
White, Scotch, Austrian, and Red Pine
DESCRIPTION OF DAMAGE:
The observable damage varies among tree species and among trees of a single species can vary in a single plantation. The most common symptom is sickly yellow needles with browned tips, although some needles may have a blotched appearance. Mites feed on needle sap and cause a small white or yellow spot at the feeding site. Many mites feeding will give the needle a stippled or rusted appearance. The pine bud mite has also been called the needle sheath mite because of its habit of feeding in the sheath at the base of the needle. Needles need to be pulled apart in order to see the mites. 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. Damage often appears first on the south side of the tree and may or may not spread around to the other sides.
IDENTIFICATION:
The pine bud mite is a small mite in the family Eriophyidae.
These mites are some of the smallest arthropod plant pests known. They are creamy white and about 0.2 mm in length. Their bodies gradually taper toward the end and somewhat resemble a carrot in shape. Their legs are held at the front of the body. They have piercing sucking mouthparts and do not have wings.
LIFE HISTORY:
These mites breed continuously and are active in cold weather, but populations tend to build up in the spring. Eggs, nymphs and adults can be found at all times. They spend most of their entire lives between the needles. They move from tree to tree with the aid of wind, birds, or by walking on touching branches.
CONTROL:
In Virginia the best time to treat is in March or April, although treatments anytime these mites are discovered will be effective. Unlike spider mites, pine bud mites are controlled best with Sevin, but Kelthane will give some control. Horticultural oils will give good control in late winter, but the oil will remove the "waxy bloom" from the needles and give an oily appearance. Oil should be used at the lowest rate because it may cause some burn as well. The presence of damage should be used as an indicator to treat, because trees can support low non-damaging populations of this pest. If mites and damage are found, it is best to treat the whole stand.
REMARKS:
The damage of this mite can mimic other abiotic problems such as air pollution injury or drought and these need to be taken into consideration when diagnosing the problem.
Further Reading:
Drooz, Arnold T., Editor. 1985. Insect of Eastern Forests, USDA, Forest Service. Miscellaneous Publication No. 1426.
Superintendent of Documents, U.S. Gov. Printing Office, Washington, D.C. 20402.
Johnson, W. T. and H. H. Lyon. 1991. Insects that Feed on Trees and Shrubs, 2nd Edition, Revised. Comstock Publishing Associates, a division of Cornell University Press, 124 Roberts Place, Ithaca, NY 14850. 241 color plates, 560 pages. ISBN 0-8014-2602-2.