March 16, 2006

Christmas Tree Scouting Report No. 1 - March 16, 2006

Welcome to an unusually warm start to the 2006-growing season. White pine weevil adults were found in traps in Bedford, Carbon, Perry, Schuylkill, and York counties this past weekend when temperatures climbed through the 70s and into the low 80s on Monday in many parts of Pennsylvania. With this unusually warm weather many growers have been asking about white pine weevil emergence. I’m glad to hear it is of concern to so many of you, because it is one of the first pests to appear in early spring after the temperatures exceed 50 degrees. Adult weevils emerge from hibernation beneath host trees and feed for a short period before mating and laying eggs.  They lay their eggs beneath the bark of the main terminals, usually within two weeks of emergence. Early detection of adults in the spring allows you to apply chemicals before eggs are deposited, providing the best control. Pyramidal traps (a.k.a. Tedder traps) are the most efficient method for monitoring. Information on purchasing and using these traps can be found on our web site.

You are probably wondering if you should apply your first weevil spray now that adults have been found in traps.  With temperatures predicted in the high 40s -- and lows below freezing -- over the next several days, weevil activity will probably cease. The chance of weevils coming into contact with-- or ingesting the chemical would be slim, and by the time temperatures are predicted to rise significantly, the residual effects of most chemicals would have lapsed.  Insecticides generally work best at temperatures above 50 degrees, so you should watch the forecast for your area and wait until temperatures average above 50 degrees before spraying.

Other weevils that might appear in traps are the northern pine weevil, pales weevil, and the pine root collar weevil. Applying a registered insecticide to freshly-cut Scotch pine stumps in early spring controls both northern pine weevils and pales weevils. An insecticide registered for use against root weevils can be applied to control pine root collar weevils. Damage from these other weevil species was more of a concern when Scotch pine was the dominant species grown for Christmas trees.
Other early spring pests to be scouting for now are: nymphs of Cooley spruce gall adelgids on Colorado blue spruce and Douglas fir; eastern spruce gall adelgid nymphs on Norway spruce; rust mites on white pine and spruce; and overwintering spruce spider mite eggs on true firs.