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May 2, 2003

Christmas Tree Scouting Report -
Number 6

Welcome to the Christmas Tree Scouting Report for the week ending May 2. The next report will be available after 4 PM on Friday May 9. To receive a FAX of this week's message, please call (814) 865-1636. To report pest activity at your location or request email report, please call 717 772-5229. 

Rhabdocline is probably on a lot of growers' minds at this time. In Dauphin, Lancaster and Perry counties this week, Douglas fir has reached 10% bud break. Infected areas on the undersides of needles are swollen and splitting open, exposing the infectious orange spores. In Berks and York County, growers are close to 10% bud break and will be spraying in the next couple days. In Chester, Northumberland, Schuylkill and Snyder counties growers visited are still a week or more away from bud break and timing will depending on warming temperatures in the coming weeks. Remember bud break can vary from field to field, so take the time now to quickly walk through different blocks on the farm and evaluate your trees to time your sprays accordingly.

Now is the time to be spraying for balsam twig aphid. The overwintering nymphs have matured and stem mothers are beginning to produce offspring. It is these offspring that feed on the sap of developing needles causing them to twist and distort in shape. This is both aesthetic damage and stunting of new growth. Balsam twig aphids were found in early breaking buds on Canaan and concolor fir in Berks, Lancaster, Northumberland and York counties. These aphids can also be found feeding in the newly forming cones on fir before buds break. Many lady beetles were noticed at some sites where this aphid has been causing damage. If you are concerned about harming the lady beetles, Insecticidal Soap is labeled for the aphid and will preserve the beneficials.

Spruce spider mites were hatching on Colorado spruce in Northumberland and Snyder counties and on Canaan fir in Lancaster County. Growers should check their own trees to decide if the overwintering eggs have hatched and applications of miticides are needed.

White Pine weevil adults are still being trapped at our Perry County monitoring site. This week, terminals examined from white pines at this site revealed that the eggs are hatching. In Chester County damage and adult weevils were found on Norway and Scotch pine. Only feeding damage was seen on Austrian and White pine. When the terminals were examined on these two species, eggs were present only in the white pine. White pine weevil damage to Scotch and Austrian pines are unusual but these species are known to be susceptible.

Eastern gall rust also known as pine-pine gall is sporulating in Dauphin County on Scotch pine. This fungus kills individual branches and if the main stem is infected, the entire tree can die. The fungus causes swellings on trunks or branches and when in the infectious stage, cream-colored blisters filled with orange spores are located on the surface of galls. Removing galls before they produce spores is the best control.

Pine spittlebug was found on Scotch pine this week in Perry County. Unless abundant, this insect seldom does significant damage. Sphaeropsis shoot blight may invade weakened pines through spittlebug feeding wounds causing shoot tips to turn brown. Control is applied to the adults after they mature and discontinue producing spittlemasses.

The next report will be available after 4 PM on May 9, 2003.