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May 5, 2004

Christmas Tree Scouting Report -
Number 6

Welcome to the Christmas Tree Scouting Report for the week ending Wednesday May 5, 2004. The next report will be available after 5 PM on Wednesday May 12th. To receive a FAX of this week's message, please call (814) 865-1636. If you would like to receive this report via email, please send a request to rdlehman@state.pa.us and you will be added to the distribution list. Frequently, the email/fax report contains more information than we are able to fit into the 3-minute recording. To contribute observations to this report, please email to the address above or call (717) 772-5229.

This week numerous Douglas fir needle midge adults were found in traps set in Bucks and York counties. When the new growth was observed eggs were found on the bottom of new needles and on the bud scales. In Lehigh county adults were found flying around the base of Douglas fir and landing on the new growth. No midges were found in traps in Schuylkill County, even though the trees exhibited damage in 2003. This new pest on Douglas fir in Pennsylvania was first found in the summer of 2002 in Lehigh and Northumberland counties. In 2003, we started to survey to determine how wide spread this insect was. At the end of 2003, fifteen southeastern counties were documented with Douglas fir needle midge with Bucks and Lehigh counties having the highest infestations. We plan to continue with the survey during the summer of 2004.

The best way to control this midge is to spray when adults are present. Timing can be enhanced by setting emergence traps in early April to monitor for adult emergence about the time of bud break. This midge is about 1/8th of an inch long with an orange colored abdomen and black head. The females have a long ovipositor off the tip of the abdomen whereas in the male, this is absent. The eggs are orange with a red spot and can be found only with the aid of a hand lens. Controls for this pest are targeted toward the adults and must be applied before the females begin to lay eggs. When midge emergence coincides with 10% bud break, chemicals for both Rhabdocline and midge control can be applied simultaneously.

Growers who applied their 1st spray for Rhabdocline needlecast last week should be planning their second spray one week after the first followed by a third spray two weeks after the second. Growers who choose to apply Bravo Weatherstick should consider changing to a different formulation to avoid misuse of the material. Weatherstick labeling indicates applications should be made every three weeks. This product protects foliage very well but does nothing to protect new growth that has come on after the fungicide was first applied. Repeated applications of a properly labeled material are needed to protect all the new growth. This cool wet weather has been ideal for this fungal disease to re-infect new needles and if it continues into the season a forth spray may be needed.

Pine bark adelgid nymphs are on the new expanding candles of white pine in Dauphin and York Counties. Normally this insect does not cause significant damage to healthy, more mature trees and the introduced multicolored Asian lady beetle has helped keep this pest in check. Smaller, stressed white pines can be stunted, turn chlorotic, or even be killed if the infestation is left to flourish.

In Perry County this week, Cooley spruce gall adelgids were found feeding in the new grow of Douglas fir and on the new growth of Norway spruce the eastern spruce gall adelgid was found. This is an indication that the control period for both of these adelgids has pasted and the next opportunity will be in the fall.

Pine-pine gall or eastern gall rust was found sporulating on Scotch pine in Dauphin and Perry counties. These galls can be found as swellings on the trunk or branches of trees and when infectious, expose orange colored spores on the surface of the gall. Control is best achieved by removing galls from trees before they produce spores that can infect other pines. Scotch pine is the most frequently host for this pest.

Eggs of the white pine weevil are beginning to hatch in the terminals of white pine in Perry County. Once the eggs are laid in the terminals control cannot be directed at the eggs or the larvae. Look for stunted and browning terminals in June and prune out and destroy infected terminals to eliminate further damage to the growth of the tree.

Those of you who scout your trees using a hand lens might notice little black spots sporadically spaced on the undersides of the needles and on the bark of Douglas fir and spruce. This fungus is known as "fly speck" and causes no harm to conifers. The black spots can easily be scraped from the surface of the needle and bark.

Lilac is beginning to bloom in the Harrisburg area. This plant is usually a host indicator for emergence of pine needle scale crawlers. Keep your eyes open for the tiny red crawlers and apply a registered insecticide when they are active.

The next report will be Wednesday May 12th. after 5:00pm.