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May 14, 2008

Christmas Tree Scouting Report #8 - May 14, 2008

This report is compiled by Sarah Pickel of the PA Department of Agriculture from the scouting recordings of Tim Abbey of Penn State's York County Cooperative Extension, Steve Derstine of JC Hill Tree Farm in Schuylkill County, Ann Echard of Penn State University, Sandy Gardosik of the PA Department of Agriculture, Doc Nesvold of Tannenbaum Enterprises in Schuylkill County, Susan Newhart of Arcadia Trees in Indiana County, Mel Nye of American Green Corporation in Schuylkill County and Cathy Thomas of the PA Department of Agriculture.

This week, in Schuylkill County, crawlers of Pine Needle Scale were just beginning to emerge.  This scale has a white, oyster shell-shaped covering with a yellow spot on one end.   They range in length from 1/16" ­ 1/8".  Crawlers will be red to yellow in color.  Pine needle scale can affect all pine species, as well as spruce and fir species and Douglas fir.  The time for treatment is after egg hatch and before the new crawlers settle and begin to wax over.  Since egg hatch is just beginning, growers may want to wait to take action until more crawlers are exposed.

In Adams County, nymphs of the Pine Bark Adelgid have hatched and are moving into the candles of white pine.   The fuzzy white covering of this insect can give the bark of pines a white washed look.  This is mostly a cosmetic pest, but if populations are heavy of this pest, it can affect tree vigor.  In low populations, feeding from predators, such as lady beetles, can control this pest.  If chemical control is necessary, this can be done during the fall or spring with horticultural oil to smother the overwintering mature females.  Insecticide treatment can be applied when nymphs emerge and move to the candles, but since beneficial predator insects are out at this time, it is best to use a softer insecticide.

Growers in Schuylkill County have already applied their second fungicide treatment for control of Rhabdocline Needlecast on Douglas fir.  The recommended treatment program suggests that growers spray a third spray two weeks after this.  If wet weather persists, or if growers are also dealing with Swiss needlecast, then a fourth application two to three weeks after the third spray is recommended.

Also in Schuylkill County, adults of the Douglas fir needle midge are still active.  It is recommended that growers apply insecticide treatment right at early bud break, but if the midge are still active, as second application of an insecticide with translaminar qualities might give better control.  Growers who have not applied the early treatment will likely see damage, even if a later spray is applied.

Eggs of the cryptomeria scale have not been observed yet in Schuylkill County, but adult male scale insects have been observed on sticky traps, so the eggs may be appearing in the next week or two.

In Adams County the galls of Eastern spruce gall adelgids are starting to form at the bases of the new buds on Norway spruce.  Although this swelling has not been observed yet with the Cooley spruce gall adelgids on Colorado blue spruce, it could be happening now in other areas, or should begin within the next week.  Once these galls form, the adelgid nymphs will be protected inside of the galls and insecticides will have no effect.  Mechanical control can be achieved with these pests later in the summer, before the galls begin to open.  Pruning these galls off in the summer and removing them from the field will prevent the release of the adult adelgids.

As for the Cooleys on Douglas fir, while the best time for control is in the fall or spring before they have a chance to wax over, some growers may ask about control at this point in the season.  The nymphs of the Cooleys have moved to the new growth in Adams County, where they are more protected and will do damage.  Growers could get some control from a spray at this time, but if they must spray, a softer pesticide would be best as beneficial predator insects are out at this time.