March 29, 2006

Christmas Tree Scouting Report No. 3 - March 29, 2006

White pine weevils were reported in Columbia, Lebanon,  Perry and Schuylkill counties. With temperatures beginning to average above 50F and expected to continue we can expect adult weevil activity. When adult weevils begin emerging from beneath host trees they fly or crawl to the terminal to feed and breed. Look for small pinprick size feeding holes below the terminal bud cluster. On sunny afternoons you can catch the sun glistening off the sap seeping from the feeding punctures and if you’re lucky you might spot an actual weevil. If you have pyramid trunk traps for monitoring early emergence of these adult weevils, place them in the field within the next day or two. For best results place traps within the row and beside a tree that was attacked last year.  When you begin to catch weevils, you should spray the top 1/3 of the trees within the next few days, followed by a second application about two weeks later.

Eriophyid mites are beginning to hatch on Concolor fir and Colorado blue spruce in Snyder County. Eriophyid mites are wedge-shaped, soft and wormlike, with only two pairs of legs just behind the mouth parts. These mites are extremely minute (0.10 to 0.33 mm long) and impossible to see with the naked eye. With the aid of a 10-20X-hand lens, it is usually possible to see the mites on the needles, where they cause russeting, bronzing or silvering. The mites, which are found on the undersides of the needles, are cream colored on Concolor fir and orange on Colorado blue spruce and Norway spruce. To control these mites use a registered general miticide, a formulation of Sevin or oil. Remember: oil removes the blue bloom from glaucous trees. On white pine, the pine sheath mite (which is also an eriophyid mite) may cause damage. In the early spring these mites can be found at the base of the needles and/or between the needle bundles when needles are pulled apart. This mite first causes chlorosis then browning of needles and is sometimes confused with phytotoxicity damage.

On White Pine, pine bark adelgids are beginning to lay eggs beneath the fluffy white wax coverings they secrete over their bodies. Only after you pull back the cottony, white coverings will you find the black, teardrop-shaped, nondescript insect and light pink eggs. This insect usually congregates on the trunk and limbs, and in the early spring around the buds before they begin to elongate. It usually is not a problem because it is controlled by natural enemies such as syrphid fly larvae and ladybird beetles. However, smaller, stressed white pines can be affected if the infestation is allowed to flourish. Needles may turn yellow and drop prematurely, and small trees may be stunted or killed. To control this insect, dormant oil can be applied in early spring before new growth starts. Otherwise a registered insecticide with a spreader sticker to help penetrate the waxy covering of the insect can be used.

If you have any pest information to report please email or phone Sandy Gardosik at or (717) 772-0521 and give pest, host plant and county where observation was made and I will include this information in the next report.