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March 30, 2005

Christmas Tree Scouting Report -
Number 1

Welcome to the Christmas Tree Scouting Report for the week ending March 30, 2005. The next report will be available after 5 PM on Wednesday, April 6. 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.

White pine weevil adults are beginning to emerge in southern Adams County. No feeding damage was observed on the terminal where the white pine weevil adult was found. No weevils were found in traps at our monitoring site in Perry County. You should begin scouting those areas of your fields where damage occurred last year. Look for either the adult weevils on the terminals, or for pinhole-size feeding holes with oozing sap below the terminal cluster of buds. This weevil is ¼” long with its head tapering into a snout. Its body is brown with brick-red spots and two white spots toward the tip of the wing covers, creating a white line. For those growers monitoring with traps it is important to keep the baiting solutions at reasonable levels. As soon as either damage or weevils are observed on terminals or in traps you should apply a registered insecticide to the top 1/3 of trees. A second application may be needed.

Cooley spruce gall adelgids were observed on the undersides of Douglas fir needles in York Co. For those growers who had damage last year either on Douglas fir or Colorado Blue Spruce, or on Norway with eastern spruce gall adelgid, and did not spray in the fall, there is still time to do an early spring application.

Eriophyid mites are beginning to hatch on white pine, blue spruce and the true firs (genus Abies) in Adams and York Counties. Even with a 16X-hand lens these mites can be difficult to see. They can be either a creamy white color on pines and firs or a salmon color on spruce. Look for slowly-moving, wedge-shaped mites at the base of the undersides of needles. On white pine this mite is known as the “pine sheath mite” because of where it feeds. Later in the season once the new needles begin to expand and the sheath is present, you need to pull the needles apart and look in the sheath at the base of the needles to find these mites. At this time of the year the overwintering eggs and mites can be found on the undersides of needles near the base. These are cool weather mites that become active very early in the season, before the spruce spider mite egg hatch. When populations become heavy, needles take on a silvery or cholorotic appearance. Remember when deciding on control measures that Sevin is a broad-spectrum insecticide that can cause spider mite outbreaks on some host species. If you use dormant oil, apply it before new growth starts, when temperatures are around 50 degrees, and there is no danger of freezing before spray dries. Horticultural oil will remove the blue bloom from glaucous trees.

Balsam twig aphid eggs were found on Canaan and Fraser firs in Adams and York Counties. The nymphs of these aphids cause stunting and curling of new needles. If populations get heavy enough, sooty mold can grow on the excessive honeydew expelled form these aphids. The overwintering eggs will begin hatching in the next couple weeks and the resulting nymphs will mature into stem mothers before buds break. It is the nymphs produced by the stem mothers at bud break that cause damage to the new needles. Sprays are best applied when most over wintering eggs have hatched and before buds break.

Pales weevils were found around fresh cut white pine stumps when “duff” needles were pulled back from trunk. To prevent damage from this weevil, stumps cut during last season’s harvest of Scotch pine should be treated. If populations of pales weevils are high in field, stumps of other pine species should be treated also.

Lady beetles are beginning to come out of hibernation and were found on eastern white pine where they feed on the pine bark adelgid. This adelgid overwinters as nymphs, and they cover them selves with white waxy threads as they mature. This adelgid can be found between buds and also on the trunk. It is generally not a serious pest, but may weaken previously-stressed trees.

Now is the time to do some pre-season scouting before the new growth starts. When scouting for spruce spider mite on true firs and Douglas fir look for browning at base of needles. If mites are present overwintering eggs will be found on the bark at base of needles or on the new buds. Yellowing spots on the tops of true firs, Spruce and Douglas fir could reveal cryptomeria scale or elongate hemlock scale on the undersides of needles. In all pines, the white, elongate bodies of pine needle scale are easy to detect at this time of the year. Symptoms of rhabdocline needlecast are evident on Douglas fir. Infected trees have distinct red-brown blotches on the needles. Removal of the overwintering eggs of the bagworm now, may eliminate the need to spray or at least lessen the numbers. More on managing these pests and others will be discussed in future newsletters throughout the growing season.

The next report will be available after 5 PM on April 6.