June 11, 2008
Christmas Tree Scouting Report #12 - June 11, 2008
This report is compiled by Sarah Pickel of the PA Department of Agriculture from the scouting recordings of Jim Fogarty and Kyle Halabura of Halabura Tree Farms, Susan Newhart of Arcadia Trees in Susquehanna County, and Sandy Gardosik, Karen Najda, and Cathy Thomas of the PA Department of Agriculture.
In Dauphin County, Cryptomeria scale crawlers have begun to emerge on Fraser fir. These scales can be found on any true fir, Douglas fir, hemlock and even spruce species. The crawlers are the nymphs that have hatched from the eggs underneath the adult female scales. They will appear as bright yellow, round, flat discs on the needle. If looking closely enough with a hand lens, growers can see small antennae and faint eyes. The crawlers are the stage that is susceptible to pesticides because they have no scale covering yet. Soon they will settle and begin to form their waxy covering. As stated in last weeks report, the recommended chemical treatment for Cryptomeria is two sprays, 7–10 days apart, beginning when the crawlers first emerge. As of yesterday, crawlers were not found in parts of York and Schuylkill Counties, but growers should be monitoring to see when crawlers emerge in their fields.
As for Elongate Hemlock Scale, crawlers were seen this week in Adams and York Counties on Fraser, Grand and Canaan Fir. These scales can be found on true firs, Douglas fir, hemlock and spruces. The crawlers are bright yellow, but they have more of an oval shaped appearance than the crawlers of Cryptomeria. This scale overwinters in several life stages, so crawlers for this scale may emerge several different times this summer. The recommended spray program for this pest is either three sprays, four weeks apart, or four sprays, three weeks apart.
Bagworm larvae have started to emerge from their cases this week in Dauphin and Schuylkill Counties. These pests can be found on any conifer species. The tiny larvae descend from the casing on fine silk threads and attach to the underside of new needles. Growers may see the threads glisten in the sunlight before they see the actual larvae. Only one pesticide application is necessary for this pest if growers wait about a week after emergence to spray, so as to target the maximum number of larvae. If growers don’t know how long the larvae have been out, they can open the bagworm casings to see if there are still larvae inside.
Growers may be noticing the next generation of Cooley spruce gall adelgids on their Douglas fir. At this point in the season, the needles will be exhibiting the kinked symptom of the adelgid feeding. There will now be eggs under the fluffy, waxy covering. These eggs could hatch as nymphs which will move to the second flush of growth on Douglas, or they could be winged adults that will migrate to Colorado blue spruce. Because the Cooleys have a varied emergence rate at this point of the season, it is not recommended that growers attempt to treat them now. The best times for treatment are in the Fall or early Spring, targeting the overwintering nymphs.