Monday, May 4, 2009

Landscape - Scale Insects: Pine Tortoise Scale

This is the 21st in a series on scale insects in the landscape. This post is on the Pine Tortoise Scale. Information is from the University of Maryland.

Pine Tortoise Scale (Toumeyella parvicornis), Family Coccidae

Plants Damaged: Scots pine and Virginia pine are the two species most severely attacked by pine tortoise scale, but red, white and loblolly, Austrian pines are also affected.

Damage Symptoms: These insects also produce honeydew, a substrate for the growth of a sooty mold fungus that blackens affected plants. Yellowing of foliage and dieback of branches.

Life Cycle: Pine tortoise scale insects overwinter on host twigs as immature females. They are reddish brown and slightly wrinkled, but shiny, when they first begin to develop on the twigs. The females resume growth in the spring, reaching maturity in June. The, eggs are laid beneath the female's body (several hundred per female!) and the ambercolored young scale crawlers begin to emerge in June or early July.

Monitoring: This scale derives its name from the characteristic appearance of the mature females. They look like tiny tortoises up to 1/4 inch in diameter and are most often found on 1- and 2-year-old shoots of "hard" pines.

Control: Soil injections of imidacloprid are effective or apply horticultural oil and Distance when crawlers are active in June.

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

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