Saturday, May 30, 2009

Landscape and Nursery - Pine Needle Scale

The following is information on pine needle scale. Crawlers are now active in Delaware

Pine needle scale, Chionaspis pinifoliae, crawlers are actively searching for places to settle and feed. Crawler activity often begins when Forsythia intermedia is in full bloom, however peak crawler activity is 498 (range 63-1046) GDD base 50 . Crawlers are light purple in color until they settle and turn light yellow with a dark longitudinal line down the center. Crawlers, found on needles, may spread by crawling, wind or birds. This scale prefers pines, especially Scotch and mugho, but may also be found on firs, Douglas-firs and spruces. Adults appear as white oyster-shaped scales and when populations are large, give plants a frosted appearance. Untreated heavily infested plants may cause needles to turn yellow to brown and may cause twigs or branches to die. Females lay about 40 reddish colored eggs during the summer around 1622-2745 [2053 peak] GDD base 50 . The second generation of crawlers usually begins at 1791 GDD base 50 . Another closely related scale, Chionaspis heterophyllae (commonly called PINE SCALE or PINELEAF SCALE), is known to feed on pines predominately, but has been reported on fir and spruces. The differences between the two are only noticeable under a microscope.

Natural enemies such as the twice-stabbed lady beetle and parasitoids attack this scale species. Treatment options include: horticultural oil, insecticidal soap, dinotefuran, acetamiprid, pyriproxyfen, acephate, and synthetic pyrethroids such as deltamethrin. In some cases, such as on Christmas tree farms, removal of heavily infested trees reduces the likelihood of other nearby trees becoming infested.

Pine needle scale giving a frosted appearance. Photo by Whitney Cranshaw, Colorado State University,

Information from Brian Kunkel, Ornamental IPM Specialist, UD.

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