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August 21, 2008

Update on the Second Generation of Cryptomeria Scale

Cryptomeria scale eggs have begun to hatch this week in Schuylkill and York Counties.  In Schuylkill County, crawlers were found moving on the undersides of Fraser fir needles on Monday at 2100 growing degree days.  On Tuesday in York County, crawlers were also seen on the move on Fraser fir.  This period, when the crawlers are moving and have not formed a scale covering yet, is the time they are most vulnerable to insecticide or horticultural oil applications.  Growers should use a hand lens to monitor susceptible trees for crawler emergence.  The scale is typically found on the lower branches, toward the inside of the tree and will be on the underside of the needles.  Crawlers appear as small yellow discs that may be moving.  One scouting trick is to hold a white piece of paper or paper plate under these branches and hit the branches so that crawlers will drop onto the paper/plate.  It may be easier to spot the moving crawlers this way.  When you find crawlers, apply an insecticide or horticultural oil spray.  Follow this application with a second (and possibly third in bad infestations) a week to ten days later.

This will be the last report of the 2008 growing season.  It is compiled by Sarah Pickel.  Thanks to Jim Fogarty of Halabura Tree Farm in Schuylkill County and Cathy Thomas of the PA Department of Ag for supplying scouting information.