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June 15, 2005

Christmas Tree Scouting Report -
Number 12

Welcome to the Christmas Tree Scouting Report for the week ending May 11, 2005. The next report will be available after 5 PM on Wednesday, May 18. To receive a FAX of this week’s message, please call (814) 865-1636. If you have pest activity to report, or would like to receive this report by e-mail, please leave a message at 717 772-0521 or e-mail sgardosik@state.pa.us and your name will be added to the distribution list.

The eggs of Cryptomeria scale are beginning to hatch on Canaan and Fraser fir in Adams, Dauphin, Juniata, Lancaster and York Counties. The majority of the crawlers are still under the female’s protective cover but a few are exposed on the needles. In Huntingdon County, females are just beginning to lay their eggs. Scale control is generally directed toward the crawler stage and at least two applications, 7 to 10 days apart are recommended. A third spray may be necessary if crawlers are still emerging.

Eggs of the striped pine scale Toumeyella pini are beginning to hatch and crawlers can be found on the bark and needles of Scotch pine. This scale’s life cycle and control is similar to pine tortoise scale Toumeyella parvicornis. Here in Pennsylvania the majority of the populations are the striped pine scale. It is the adult females that overwinter and become noticeable by the spring. At this time of year, female scales are about 4mm long, helmet shaped, and reddish-brown with white striped markings. Needles around the scale tend to be black from a sooty mold that grows on the sugary waste product secreted by the scale. Crawlers are salmon color and resemble small bits of sawdust on the needles and bark. Females will settle on the bark and the males out on the needles. This is a soft scale which feeds in the phloem so an insecticide with systemic activity will work better than one that works on contact.

Bagworm are about 1/8 – ¼ inch long and are beginning to do damage to needles on Douglas fir in Juniata County and Blue spruce in Lancaster county. When the bagworm larvae first emerge they feed on the surface of needles causing them to brown; once they reach about a ¼ inch they can consume whole needles. If you had problem with bagworm last year you may want to spray a registered insecticide in the next couple days.

The infectious period for rhabdocline is coming to an end. Once the new growth begins to harden off and nighttime temperatures stay above 55F rhabdocline is no longer infectious. A small percentage of active spores were found in Dauphin, Huntingdon and Schuylkill counties. Most growers should have applied their third spray by now and those who have had problems with Swiss will want to make sure they apply a fourth if they have not done so already.

Spruce spider mites were found feeding and causing damage to the new growth on Fraser fir in Juniata and Lancaster counties. Since the spruce spider mites have just begun to move onto the new growth and damage is not yet significant, it would be advisable to control these mites now before more damage is done and eggs are laid to produce a damaging fall population.

Over wintering eggs of the Balsam twig aphid were found on the new growth of Fraser fir in Franklin County. This is the end of this insect’s life cycle for the season. When these eggs are first laid they are light green with long silver fibers and as they age the green turns to black. With a hand-lens you can find these eggs on the twigs and the base of needles of this year’s growth. The next time to control this insect will be before bud break in spring of 2006.

Elongate hemlock crawlers are out on the new growth of grand fir in Adams County. This scale becomes more active as the temperature warms. If you know you have this scale pest, I would begin a spray program now and continue with a total of three sprays at four-week intervals.

The next report will be on Wednesday the 22 nd after 5:00pm.