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June 22, 2005

Christmas Tree Scouting Report - Number 13

Welcome to the Christmas Tree Scouting Report for the week ending May 11, 2005. The next report will be available after 5 PM on Wednesday, May 18. To receive a FAX of this week’s message, please call (814) 865-1636. If you have pest activity to report, or would like to receive this report by e-mail, please leave a message at 717 772-0521 or e-mail sgardosik@state.pa.us and your name will be added to the distribution list.

Damage from the white pine weevil is now evident in the leaders of Colorado spruce, Norway spruce, Douglas fir, white pine, and Serbian spruce in Chester, Northumberland, Schuylkill and York counties. This weevil is known to damage all varieties of Christmas trees. However, I have not seen damage in the true Firs or Abies genus this year. Growers are beginning to walk their fields and examine terminal leaders that are showing symptoms of wilting. When the bark is peeled back from infested leaders, cream-colored larvae and wood-chip cocoons are found. These chip cocoons are an indication that the larvae are mature and beginning their next stage of development, the pupae. Adults will begin to emerge in mid-July and into fall. If you find leaders infested by weevil larvae, and wish to control the pest with mechanical methods, make sure the pruning cut is made down into the clean wood and all infested wood is removed from the field and destroyed. This will prevent larvae from maturing to adults, and emerging in the same field. You can then train a new leader to bring the tree back into an acceptable shape.

There are still eggs of cryptomeria scale hatching and both crawlers and settled crawlers were observed on the undersides of needles of Fraser fir in Chester and Northampton counties and on concolor fir in York County. The eggs of this scale hatch over a few consecutive weeks so two to three spray applications about ten days apart are needed. Sprays should continue until all eggs are hatched. This scale has a second generation with eggs detectable in the later part of July with crawler emergence about mid-August.

Damage from the Douglas fir needle midge is becoming easier to detect when needles are examined. Damage is evident in Chester, Schuylkill and York counties this week. Areas of needles infested with the midge are yellow and beginning to swell. Usually the needle is kinked where the larvae has created a gall. However, this is not always true and some straight needles with galls can be found on most trees. If more than one area of a needle is infested, that needle can have several bends or crooks. As the insect develops the gall hardens and darkens and the needle may brown from the gall out to the tip of needle causing needles to break.

We received a report of Douglas fir needle midge causing damage on Long Island, New York this week. Other states reporting this as a new pest in the last few years include Maryland, Michigan, and New Jersey.

The hot temperatures last week may have slowed down spider mite populations but growers should be monitoring trees at their own location to make sure they do not rebound and cause significant damage. Monitoring should continue on a regular basis, and be more frequent in cooler weather.

The last report for the 2005 season will be Wednesday June 29 th after 5:00pm.