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April 9, 2008

Christmas Tree Scouting Report #3 - April 9, 2008
Compiled by Sarah Pickel, PA Department of Agriculture.

Yesterday, in southern Adams County, two weevils were recovered from a growers Teddar’s trap.  One weevil was small (< 1 cm), with a mottled brown appearance with two white spots on its wing covers. This weevil was either an eastern pine weevil, or a white pine weevil.  The other weevil was a larger (> 1 cm), brown weevil, believed to be a pales weevil.  The pales weevil can cause “flagging” damage, or browning of side branches, in pines and other conifers, by feeding on the bark around these branches.  If you’ve had a problem with this weevil, management calls for the removal or insecticidal treatment of scotch pine stumps from this past season’s harvest (pales preferred host) before pales weevils lay their eggs in the stumps in early to mid April.  Growers monitoring weevil traps in Adams, Lancaster, Schuylkill, Susquehanna and York Counties still have not seen white pine weevils in the traps or on tree leaders.  Temperatures throughout this past week have remained cool and since last week’s report, growers in Schuylkill County have not added any Growing Degree Days to their total of 4.5.  As the temperature warms this week, growers should be looking for weevil emergence.

In Adams, Schuylkill and York Counties, scouts are seeing Eriophyid mites hatched from eggs on concolor fir, Douglas fir, Colorado blue spruce, and Norway spruce.  For management of these mites, make sure to use miticide products labeled specifically for control of Eriophyid mites.  Growers may also be monitoring for emergence of spruce spider mite.  In Adams, Schuylkill and York counties, spider mite eggs have not hatched yet.  Be looking for mite hatch within the next few weeks.  Eggs of these mites are red in color and can be found on the twig and at the base of needles.  When the mites hatch, they have a light red appearance. To check for egg hatch, tap branches over a white sheet of paper and wait for the red specks to begin moving around.

Last week, scouts reported that cooley spruce gall adelgids on Colorado blue spruce were beginning to cover over with a light waxy coating.  This covering has continued to develop.  For cooleys on Douglas fir, however, scouts in Schuylkill, Susquehanna and York Counties have not seen the formation of this waxy covering yet.  In southern Adams County, cooleys on Douglas are just beginning to form a halo of wax around their bodies.  Insecticide treatment of these adelgids needs to be applied before the coating forms to be most effective.

Over-wintering eggs of balsam twig aphids are beginning to hatch in southern Adams County.  Monitor for these aphids on the bark of twigs surrounding those twigs showing damage from last year’s growing season.  The eggs, covered in silvery threads, give rise to the pale yellow/green stem mothers.  Insecticide treatment should be applied before these stem mothers give rise to live young, which will happen shortly before bud break.