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June 9, 2004

Christmas Tree Scouting Report -
Number 11

Welcome to the Christmas Tree Scouting Report for the week ending Wednesday June 9, 2004. The next report will be available after 5 PM on Wednesday June 16th. 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.usand you will be added to the distribution list. To contribute observations to this report, please email to the address above or call (717) 772-5229.

This week in Carbon, Dauphin, Lancaster, Lebanon and Schuylkill Counties there were still some active fungal spores of Rhabdocline needle cast. This was determined by placing infected Douglas fir needles in warm water, a simple test everyone can perform. Growers may want to consider applying a fourth spray if it has been three weeks since they made their third application.

Elongate Hemlock Scale crawlers were found on Fraser fir in Carbon County. New growth already has chlorotic spots on the tops of needles from crawlers that have settled and will remain feeding at the same site till they develop into adults. This armored scale is hard to control because the population overwinters in different stages of development. These overlapping stages continue throughout the season making control difficult because crawlers, which are the stage most affected by insecticides, do not develop at the same time. Therefore, multiple applications, at regular intervals, are needed to get control of this serious pest.

Cryptomeria scale crawlers were out on the needles in Lancaster and Lebanon Counties. In Carbon County eggs were beginning to hatch but the majority of crawlers were still under the adult female. Unlike the elongate hemlock scale, this armored scale has a single immature overwintering stage. During the growing season, development continues and stages are closely synchronized, making spray applications more effective. However, like most scale controls, two applications of a registered insecticide, 7-10 days apart, are required during crawler emergence. Cryptomeria scale has a second generation that begins to hatch about the middle of August.

Galls produced by the Cooley spruce gall adelgid were found on Colorado blue spruce in Carbon County. By late July early August these galls will turn brown and dry and the mature nymphs will emerge and molt into adults with wings. These adults will produce a sexual generation that will mate and the eggs laid by the females will hatch to become the over wintering nymphs. Galls removed now before they dry and nymphs emerge can reduce population next year but is only practical if plantations are small and populations are light. The next time to control this pest is September through November after the over wintering nymphs are present.

Winged females of the Balsam twig aphid were found on Fraser fir in Potter County. This adult form will produce the next generation that will lay the over wintering eggs for next year. The next time to control this pest will be in the spring of next year before bud break.

Striped pine scale crawlers are beginning to emerge and were out on the needles of Scotch pine in Carbon County. This scale can be controlled now or in the early spring before they become mature adults.

Introduced pine sawfly larvae were found on white pine in Lancaster and Schuylkill Counties this week. This hymenoptera larva is about one inch long with yellow and white spots on a black background. These insects feed on the needles of most pine species but are usually not abundant enough to cause injury. Unlike other more destructive sawflies this species feeds in groups when young then disperses and feeds singly causing less damage to the tree. Control is usually not necessary because natural enemies and low winter temperatures keeps this pest in check.

Already growers are reporting a lot of damage from the white pine weevil this year. Make the point to walk your fields before late July and cut out and remove any infected terminals from the field. Damage from this weevil was found in Colorado spruce, Douglas fir and white pine in Carbon County. In Schuylkill County weevil damage was found in terminals of Norway spruce and white pine.

The next report will be issued Wednesday June 16th, after 5:00pm.