May 5, 2000
Christmas Tree Scouting Report
Welcome to the Christmas Tree Scouting Report for the week ending May 5. The next report will be available after 4 PM on Friday May 12. To receive a FAX of this week’s message, please call (814) 865-1636. If you have pest activity at your location to report, or would like to receive email reports, please leave a message at 717 772-5229.
White pine weevil eggs are just starting to hatch in leaders of eastern white pine in Perry County. Farther north, in Carbon and Schuylkill counties, there was not hatch in terminals checked this week. Most of the applications for control of this pest should have been completed by now. If you have already made one application and continue to find fresh sap flow from feeding punctures in terminals at your location, you should consider a follow-up application to protect valuable trees.
Last week, Mike Masiuk, Allegheny County Extension, reported hatch of pine needle scale eggs at sites in Pittsburgh and Westmoreland County. He found the small red crawlers on several pine species. Our scouting activities in Dauphin, Lebanon, Perry and York counties did not reveal any crawler activity to date. Lilacs are in full bloom in the Harrisburg area. But, during the last several years we have not found crawlers for the first generation until the lilac bloom is ending. We will be watching carefully for crawlers during the next week or 10 days. You should also be scouting your plantation to control this serious armored scale pest of pines.
Several growers have reported damage from last year’s drought on Fraser and Canaan fir. At one site in Lehigh County, damage was noted last August and September. Drought damage can range anywhere from reduced growth and poor budset to death of the entire tree.
Spruce spider mite populations are building at sites in Lancaster and Schuylkill counties. When scouting for these pests, growers may find the mites feeding on Fraser or Canaan fir to be red while those on Colorado spruce are dark green. These are both the same species but color is related to the host on which they are feeding. In Schuylkill County, the mites are starting to produce considerable amounts of webbing, which will trap dust and dirt and enhance the appearance of damage.
In Carbon, Dauphin, Lancaster, Lebanon, and Schuylkill counties, buds of concolor have started to open. On close examination, nymphs and stem mothers of balsam twig aphid can be found feeding on the new growth.
On Fraser fir, many of the balsam twig aphids are still feeding in the green cones. At one site, a ladybeetle was observed trying unsuccessfully to reach aphids feeding in the cones. The protection afforded by the cones is not only effective against pesticides but apparently also against predators.
Budbreak is just starting at some southern locations and the aphids will soon move to the new growth. This marks the end of the control window for balsam twig aphid. In order to be successful in preventing stunting and curling of new needles, controls must be applied before budbreak.
Douglas fir budbreak has reached the 50% level in Dauphin, Lancaster, and Lebanon counties. At those locations, Cooley adelgids are already feeding on new growth. Another pest attacking the new growth of Douglas fir is rhabdocline needlecast. Under moist conditions, the spores are being released and will successfully infect needles that are not protected by a fungicide. Several growers have already applied their first spray. A second application should be made 1 week after the first and the third would follow in another 2 weeks.
European pine sawfly larvae are about ½ inch in length and consuming entire Scotch pine needles in a Lebanon County field. This is the start of the period of feeding the can cause significant damage. Removal of colonies of sawflies or spot spraying is generally most effective.
Eastern spruce gall adelgid eggs on Norway spruce in Lebanon and York counties have still not begun to hatch. Cooley spruce gall adelgids eggs at the same locations are also unhatched. However, the Colorado spruce buds are starting to open and eggs hatch will occur in the very near future. Growers who missed their spring window of opportunity for control of these gall-making pests must wait until September for another chance. Sprays directed at control of the crawlers emerging from egg clutches produced by stem mothers are generally ineffective and should be avoided.
Pine-pine gall is sporulating in Dauphin County making the branch galls very obvious due to the orange spores. Removal of trees infected with pine-pine gall should be done at any time the galls are not sporulating to avoid spread.
The next report will be available after 4 PM on May 12.