June 28, 2002
Christmas Tree Scouting Report
Welcome to the Christmas Tree Scouting Report for the week ending June 28. This is the last weekly report for 2002. We will be continuing to make pest observations, particularly watching for cryptomeria and pine needle scale 2nd generation crawler activity. When these events occur, we will make a special short report. Otherwise, the regular reports will return in 2003 with the first report available on Friday March 28. Thank you for your continued support and contributions to this pest report during the last 9 years. We look forward to our 10th anniversary for the Christmas Tree Scouting Report in 2003.
In Northampton County, fresh sawdust on last years Douglas fir stumps mark the emergence of this year's crop of Pales weevil. These weevils have always been associated with Scotch pine, particularly with fresh stumps and dying trees. However, they do reproduce on other conifers, as this observation proves. The newly emerged adults will feed on any species of conifer in the area, removing bark from the base of shoots. Eventually, the shoots die from lack of water and nutrients. These dead shoots turn pale tan and are very obvious against the otherwise healthy green needles. To prevent "flagging", as this damage is called, Pales weevil should be controlled at the stump. In fields that have severe damage, foliar sprays can be applied in late summer to kill adults as they feed. However, this method is not as efficient or cost effective as stump treatment.
In Columbia County, elongate hemlock scale is still present in all stages, including active crawlers. Trees infested with this scale are starting to take on a white, fuzzy appearance due to the white waxy threads the male scale produce.
In York County, most of the cryptomeria scales on fir are settled crawlers. The number of unhatched eggs is low and if you look hard enough, a few active crawlers can be found. For the most part, the control window for the first generation has closed. We will continue to monitor for emergence of second-generation crawlers.
The multicolored Asian ladybeetles that create concern when they overwinter in homes and barns are very active predators in Christmas tree farms. This week, adults and pupae were numerous at a site that experienced a high population of balsam twig aphid on fir. Although the aphids have since died off and only the overwintering eggs are present, the ladybeetles are reproducing on the trees and consuming some of the eggs.
At all sites visited this week, white pine weevil remains in the larval stage in chip cocoons under the bark. We are starting to see terminals that have most of the bark removed, exposing the weevil damage and pupation sites. Whether from birds or high numbers of weevil larvae causing the bark to slough off, this condition is not uncommon. Damage is very evident in white pine, spruce and Douglas fir and growers wishing to use mechanical control to reduce populations of white pine weevil in 2003, should act now to cut out and destroy infested terminals.
As expected, both spider mite and eriophyid mite numbers are starting to decline with the hot weather of the last week. Growers should continue to monitor populations with a hand lens or by beating branches over a light surface. Spider mites and eriophyid rust mites are not done for the year, they are simply waiting until temperatures are more favorable for their survival.
We still have not seen any opened Cooley or eastern spruce galls on Colorado and Norway spruce, respectively. If only a few galls are present, hand removal before the galls open is effective. However, in most plantations, the galls are widespread and mechanical control is not practical. In these situations, a single application of a registered insecticide between mid-September and October can control the adelgids.
Colorado spruce and Douglas fir in Columbia, Lebanon and Perry counties are starting to push new growth. This growth, referred to as lamas growth, often occurs in the second half of the growing season when spring is early and temperatures are high. It is not going to replace the growth frozen out by the May frost. In fact, lamas growth has fewer buds and can cause a tree to grow out of balance, requiring additional attention during shearing.
Reports of redheaded pine sawfly feeding on new growth of Scotch pine were received this week. This is the third of the three major sawfly pests of pine and often the least widespread. The larvae have yellow bodies with numerous black spots but their characteristic red-brown head capsule is what gives the pest its name. As with the European pine sawfly, spot controls are usually the most effective.
We continue to find crawlers of striped pine scale active in York County. This has been an unusually long emergence period for this soft scale pest. This pest is one of the few conifer scales that can be effectively controlled with dormant oil in spring, before budbreak.
A few larvae of pine needle midge were found on damaged needles pairs of Scotch pine in York County this week. The larvae were almost mature and will soon drop to the ground and remain in the duff until adults emerge at the end of May 2003. Controls are only effective against adult midges and timing is critical.
Eastern pine shoot borer larvae are still in shoots of Scotch and white pine. Their damage may resemble the "flagging" damage referred to earlier. However, the bark at the base of the shoot will be intact but the shoot will be hollowed. A similar species occasionally causes shoot damage to firs. However, we have never been able to determine if it is the same species as eastern pine shoot borer or a close relative. We did not receive any reports of shoot borer activity in fir this year.
The next regular weekly report will be available after 4 PM on Friday March 28, 2003.