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June 15, 2001

Christmas Tree Scouting Report

Welcome to the Christmas Tree Scouting Report for the week ending June 15. The next report will be available after 4 PM on Friday June 22. To receive a FAX of this week's message, please call (814) 865-1636. If you would like to report pest activity at your location, please call 717 772-5229.

The first crawlers of cryptomeria scale were found today, June 15, in Berks County. Early in the week, scouting in Berks, Chester, Cumberland, Lancaster, and York counties only revealed eggs. By mid-week, crawlers were present on a weeping hemlock at a residence in Dauphin County. This location is somewhat protected, with a northern exposure. Today, crawlers of this armored scale pest of conifers were active on needles of new and old growth in southern Berks County. A few of the first crawlers to emerge had already settled on the needles.

At a farm visited today in northwestern Berks, crawlers were hatching but had not emerged from under the females covering. Growers having problems with cryptomeria scale, Aspidiotus cryptomeriae, should make their first application of a registered insecticide as soon as crawlers are active at their site. For those growers tracking growing degree-days, the reading on Monday at the southern Berks site was 615 GDD base 50° F. Today the reading was 685 GDD, which is consistent with the data from the last few years of observing crawler emergence.

Striped pine scale crawlers are finally active at a York County farm. This soft scale pest of Scotch pine has been later than usual in emerging this summer. There is only one generation of this scale each year so this is the best opportunity for control. As with the cryptomeria scale, growers may wish to hold off on mowing activities during peak striped pine scale crawler emergence. Mowing activities are a possible contributing factor to spread of scale in a field.

Eastern pine shoot borer damage is evident in white pine shoots in York County. The larvae have already left their galleries in the new shoots and will overwinter in the soil beneath the tree. Damage from eastern pine shoot borer may be confused with that of Tomicus piniperda, the introduced pine shoot beetle. However, there are distinct differences that can easily separate the two pests in the field. Eastern pine shoot borer is a moth whose larvae create the galleries in the new shoots of pines. The galleries are usually packed with frass, or insect waste material. The entrance and exit holes in the shoot are more oval than round, with no evidence of pitch buildup around the opening. On the other hand, damage caused by pine shoot beetle is from the adult beetle feeding on new shoots. These minute black beetles chew entry holes into the new shoots and mine in the center of the shoot. However, they are constantly removing material from their gallery and when the shoot is opened, the gallery is free of waste material. In addition, the entrance and exit hole is usually ringed with white sap when the pest is the pine shoot beetle.

Balsam twig aphids are depositing eggs in Berks and York counties. These eggs are pale when first deposited, but darken to black with age. They are on the new growth, and are deposited singly, usually at the base of a needle. This will be the stage for balsam twig aphid for the next 9 months and controls are not effective on the eggs.

Spider mites continue to cause damage to firs at many locations. In Carbon County, spruce spider mite is damaging Douglas fir. Although Douglas fir are not favored hosts for spruce spider mite, infestations can cause severe chlorosis of needles. The base of the needle is usually most affected and may appear white when damage is most severe.

Cinara aphids continue to be active on pines. In York County they were feeding on the bark of new growth of eastern white pine. Damage from Cinara aphids is generally minor but on spruce, they may cause needles on new growth to shrivel, damage that resembles chemical burn. Cinara infested trees often support carpenter ants and may be attractive to wasps and hornets.

White pine weevil damage is obvious at all locations. Larvae are all building chip cocoons in which they will pupate. Adult emergence should begin win the next 1-2 weeks. Mechanical control is the only choice at this time of year.

The next report will be available after 4 PM on June 22.