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DCNR to resume spraying forests to combat gypsy moth damage
State woodland managers are preparing for an aerial spraying effort to combat gypsy moth population posed for spring outbreaks in the eastern portion of the state, DCNR officials said this week.

“Heavy infestations occurred in some areas last spring but our entomologists say most of that gypsy moth population collapsed, thanks to a naturally recurring fungus,” said DCNR Acting Secretary Cindy Adams Dunn. “Last year, cold, wet weather in the spring proved ideal for the fungus, deadly to gypsy moths, but we cannot always rely on the weather to be our ally.

“A continuing year-to-year gypsy moth spraying program is often necessary to suppress rebounding insect populations while protecting forest stands that may have been damaged the previous spring,” Dunn said.

A 26,433-acre suppression program in 38 treatment blocks is proposed for 2015 in six northeastern counties—Carbon, Columbia, Luzerne, Northumberland, Pike and Schuylkill—principally on state-managed parks, forests, and game lands, but also some private residential lands in Carbon County.

Though weather dependent, spraying is expected to begin in early to mid-May and be completed by the end of May or early June. Helicopters will be used in the spraying program.

Surveys across the state indicate gypsy moth populations are increasing and have the potential to cause defoliation this spring, especially in eastern Pennsylvania.

In 2014, gypsy moth populations increased in eastern Pennsylvania after several years of high populations in the northwestern part of the state. DCNR treated 1,901 acres in 42 spray blocks in May in four northwestern counties. Treated areas all were on private lands.

Bureau of Forestry experts note the state’s oak stands are especially vulnerable to gypsy moth infestation and mortality. The loss of habitat, timber and tree growth are considerable when gypsy moth populations are allowed to go untreated.

Gypsy moth defoliation in 2014 totaled 214,972 acres, and another 115,104 acres were defoliated by the fall cankerworm, a native forest insect defoliator. Aerial and ground surveys indicated a total of 431,956 acres of damage by forest pests in 2014.

Before spring 2013, DCNR last sprayed for gypsy moths in 2009, when more than 178,380 acres in 25 counties were targeted across the state. In 2008 a total of 221,221 acres of private, state and federal woodlands were sprayed in 27 counties.

“Private woodland owners and state forest visitors must remember spraying is a suppression effort and a forest management effort to protect trees from moderate to severe defoliation,” said Dr. Donald Eggen, the bureau’s forest health manager. “The gypsy moth will continue its cyclic population with ups and downs, and we cannot eradicate the insect. It’s too well-established and is here to stay.”

Forestry bureau experts identify the gypsy moth as one of the most destructive forest pests in Pennsylvania. Feeding while in the larval—or caterpillar—stage, the insect usually hatches and begins feeding from mid- to late April in southern Pennsylvania, and in early to mid-May in the northern part of the state.

Oak, apple, sweet gum, basswood, birch, aspen, and willow trees are affected the most by the gypsy moth. Older larvae also will feed on hemlock, pines, spruces, northern white cedar, and other conifers. A tree begins to significantly suffer when 30 percent or more of its leaf surface is lost.

Begun in 1972, forest insect spray programs are a cooperative effort among DCNR's Bureau of Forestry, county governments and the U.S. Department of Agriculture Forest Service's Forest Health Protection Unit.

The gypsy moth was introduced to North America in 1869 at Medford, Mass., where it was used in a silk-production experiment. The gypsy moth first reached Pennsylvania in Luzerne County in 1932, and since then has infested every county.

For more information on forest pests, visit here.

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May 6, 2015

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