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May 16, 2003

Christmas Tree Scouting Report -
Number 8

Welcome to the Christmas Tree Scouting Report for the week ending May 16, 2003. To receive a FAX of this week's message, please call (814) 865-1636. To report pest activity at your location or request email report, please call 717 772-5229. 

Pine needle scale overwintering eggs are beginning to hatch on Fraser fir in Northumberland County this week, but the few crawlers found were still under the armor covering of the female. In Dauphin, Lehigh and York counties eggs on Scotch and white pines have not started to hatch. By next week we should be seeing crawlers out on the needles at most locations. Species of pine are this pest's favorite host, but this scale can be found on other conifers, including Douglas fir, true firs and spruce. Look for tiny red crawlers the color of paprika out on the needles. This scale has two generations per season, the first in mid-May and a second in mid-July. Properly timed sprays aimed at killing the crawlers are most effective. Controls should include 2 or 3 sprays at 7-day intervals, or as stated on the label, during each crawler emergence period.

Last week, elongate hemlock scale crawlers were found out on the needles on Fraser fir in York County. This week in Columbia and Northumberland counties crawlers were also found on the needles of true firs. To gain control of this pest, a spray program should be started once the first crawlers are detected. Repeated sprays throughout the growing season are required because crawlers emerge over a period of several months.

Another scale pest of true firs is Cryptomeria Scale. The adult males of this scale are maturing and will be seeking out females for mating. Females will begin laying eggs beneath their armor coverings in the next couple weeks. At the end of May is a good time to begin scouting for the bright yellow eggs of cryptomeria scale. This can be done by turning over the scale cover and looking for eggs with a hand lens or tapping an infested branch over a paper plate and looking of eggs. This scale has two generations per year, the first in early to mid-June and the second in early to mid August. Spray applications should begin with the first signs of crawlers. Follow the labels instructions as to the length of time between spray treatments.

White Pine weevils are still being trapped at our monitoring site in Perry County. Egg hatch is at about 50% and those new leaders that have been infested this year are beginning to look stunted. Infested terminals can be cut down to healthy wood and removed from the field at this time to control this pest without the use of chemicals.
In York County, Scotch and white pines are showing dead shoot tips caused by pales weevil feeding. This damage is known as "flagging" and is caused by this weevil feeding on the bark of side shoots where they eventually girdle the branch. In heavy infestations seedlings can be killed. The best method of control is an early spring treatment of Scotch pine stumps from the previous years harvest.

Galls from the eastern spruce gall adelgid are forming in the new growth of Norway spruce in Dauphin County. A registered insecticide can be applied to control overwintering adults in the fall of this year or early next spring but spraying at this time of year is not effective.1.

Spruce spider mites and excessive webbing was found on Douglas fir in Lehigh County this week. When populations are high this mite produces webbing to help it travel quickly to a new feeding site. Damage from this mite is permanent, and the only relief is to wait until the host produces new growth to cover the discolored needles or bare branches caused from resulting needle drop.

The recently detected Douglas fir needle midge is emerging from beneath infested trees in Lehigh County. The first adults were present in our emergence traps when they were checked at the beginning of this week. The very small midges could be seen swarming around the base of the tree and up about mid-way on the branches. Occasionally they would land on needles and the females were relatively easy to spot because of their swollen red/orange abdomens. Buds had broken on most trees in this field within the last 10 days, and already a few eggs were present at the base of the new growth. These oblong, pale eggs will hatch in 1-2 weeks and the larvae will enter the elongating needles. Larval feeding inside the needle results in a swollen gall-like area on the needles. Last fall was the first detection of established populations of this pest in Pennsylvania. It has been known from the Pacific Northwest on Douglas fir and growers regularly monitor for emergence in order to chemically control this pest. Growers who are sure they have Douglas fir needle midge should make the first of two applications as soon as possible.