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March 31, 2004

Christmas Tree Scouting Report -
Number 1

Welcome to the first Christmas Tree Scouting Report for the 2004 season. In previous years we have updated the report on Friday. However, grower requests have caused us to change to Wednesday for the updates to give you the opportunity to plan activities before the weekend. Therefore, next report will be available after 5 PM on Wednesday April 7th. 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.

White pine weevils were found in traps over the past weekend in Lancaster, Perry and Schuylkill counties. The adult weevils have also been observed feeding and/or mating on the terminals of white pine in Carbon, Lebanon and York counties earlier this week. This is one of the first pests growers need to be concerned about each spring, especially if they have had problems with this pest killing terminals of their pines, Douglas firs or spruces in previous years. Now is the time for you to scout your fields, especially those damaged in pervious years. Look for tiny, round, pinprick feeding holes in the bark beneath the terminal bud cluster. On sunny afternoons sap droplet can be seen oozing from these feeding holes or weevils may be found on the terminals. This weevil feeds and mates for about two weeks before the female weevils begin laying eggs in her feeding punctures. The best control is directed against the adults, since larvae bore directly out the back of the eggshell into the terminal. If you wish to control this pest, apply a registered spray only to the top 1/3 of the tree.

Another early season pest is the eriophyid rust mite. This is a cool season mite, which is active even before the spruce spider mite. Eriophyid mites have been found on Colorado and Norway spruce in Dauphin, Lancaster and Lebanon Counties. With the aid of a 10X, or greater, handlens, this worm-like mite can be seen on the underside of needles. Damage to Norway spruce can be described as bronzing of the needles; silvering occurs on needles of Colorado blues.

The balsam twig aphid stem mothers are hatching in Dauphin, Lancaster and Lebanon Counties on true firs. This aphid overwinters as an egg and begins hatching before bud break. These stem mothers feed on the older needles and do not do any damage. About the time the buds begin to break, live young are deposited on the opening bud by the mature stem mothers. This is the generation that causes stunting and curling of the new needles. If the population builds to high numbers black sooty mold can be seen on the branches from the honeydew produces by the aphids. The best control is achieved when sprays are applied right before bud break. after the majority of stem mothers have hatched.

Lady beetles were feeding on eggs of the pine bark adelgid in Lancaster and Lebanon counties. The introduced multicolored ladybeetle is considered a pest when it enters homes to overwinter. But, each spring, when this voracious predator moves into the Christmas tree plantation to feast on pine bark adelgids and balsam twig aphids, it is definitely beneficial. Since the ladybeetle has become established in Pennsylvania, we have noted a decrease in the pine bark adelgid populations.

On Douglas fir, the Cooley adelgid nymphs are starting to produce protective waxy threads around their edges. Observations in Dauphin, Lancaster and Lebanon counties showed this pest is still at a stage where it is vulnerable to chemical control. However, with forsythia in bloom in the mid-state, the control period will be ending within the next 2 weeks. Although we did not observe any Cooleys on Colorado spruce, their stage on this alternate host usually coincides with their counterparts on Douglas. The eastern spruce gall adelgid, a serious pest of Norway spruce, was reported to have slight waxy buildup several weeks ago in Indiana County. Controls for all of the spruce adelgids must be applied before the nymphs are covered with the waxy threads, and therefore protected. If this opportunity is missed, spraying during the growing season is not effective and the next opportunity will be in the fall. Thorough coverage to the undersides of needles and branches if important to achieve good control.

In Lancaster County, spruce spider mite eggs had not started to hatch as of yesterday. This common pest can be expected to become active in several weeks.

A heavy infection of Swiss needlecast on Douglas was observed in one area of a field in York County. The damage looks like drought or winter damage till you see the rows of tiny black spores on the undersides of the needles. In the same field, rhabdocline needlecast was also present. Controls for Swiss needlecast are usually applied one week later than those for rhabdocline. Growers trying to control both needlecasts would need to plan on a fourth spray in order to handle both pests.

In Lancaster County, Pales weevils were active on fresh cut stumps of white pine. Also found at the same site were numerous weevils that look like large white pine weevils. Previously referred to as northern pine weevil, the accepted common name for these is now eastern pine weevil. Both eastern pine and Pales weevils are usually associated with Scotch pine stumps but have been occasionally reported to breed on spruce, Douglas fir and other pine species. Both weevils breed in stumps or dead and dying trees but they will do serious feeding damage to healthy trees growing nearby. Flagging of branches is common on white pine but feeding damage to terminals of Fraser fir and Douglas has also been seen. If you find active weevils on the stumps of these alternate hosts, application of a registered insecticide will get them under control. For those Scotch pine growers, remember to drench the stumps remaining from last season's harvest to prevent a build-up of this pest.

The next report will be available after 5 pm on Wednesday, April 7.