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June 30, 2000

Christmas Tree Scouting Report

Welcome to the Christmas Tree Scouting Report for the week ending June 30. This is the last report for the year 2000 reporting season. We expect to continue the service in 2001 so please check in at this number in late March 2001.

Cooley spruce galls have started to open on Colorado spruce in Schuylkill and Perry counties. As the winged adults are released from the galls, they will fly to either Colorado spruce or Douglas fir to deposit eggs. The maturation of the galls and emergence of winged forms marks the end of the mechanical control period for this year. Removing galls at this time may make the trees look better but will have not effect the population for next season. Colorado spruce and Douglas fir can be effectively treated in September through early October when the overwintering forms are vulnerable. Fall applications provide excellent control and the spraying conditions are generally better at this time of year. As with spring controls, thorough coverage is important.

We continue to see spider mites active on spruce and true fir at many locations. In Carbon County, these mites have damaged even large Douglas fir trees. To prevent damage, growers must be regularly monitoring populations and apply controls when populations are building, before the damage occurs.

On Scotch pine in Perry County, larvae of eastern pine shoot borer, are completing their development. The death of branch tips caused by this moth borer superficially resembles pine shoot borer damage. However, pine shoot borer exit holes are perfectly round while Eastern pine shoot borer exit holes are oval.

In Schuylkill County, white pine weevil larvae are also completing their development in the terminals of eastern white pine. For the next few weeks, growers can still be effective in reducing populations of this pest by cutting out the damaged terminal and destroying the material. This will certainly not change the damage done this season, but will reduce the number of weevils available to lay eggs in the terminals next spring. When cutting out damaged terminals, remember to remove the clippings from the field. Larvae or pupae present in the cuttings can complete their development if the terminals are left on the ground. Also, be sure to cut the terminal down to the good wood to be sure you get all the larvae.

Bagworm larvae continue to develop on Colorado spruce and Fraser fir in York County. The ½ inch bags are easy to spot hanging down from branches that have missing needles. Although not practical for large areas, handpicking of bags can be effective for small populations. Remember to place the larvae in a can or bag to be destroyed later. If they are dropped on the ground, the larvae can find their way back onto the tree and continue to feed.

We would like to thank everyone for his or her support of the PENN-IPM Christmas tree scouting report during the last 6 years. We look forward to continuing the service next year. 

Thank you.