Pennsylvania's Christmas Tree Scouting Report
Presentation created & presented by Sarah Pickel, PA IPM Program; PA. Dept of Ag
DOUGLAS-FIR BUD BREAK: Bud break is happening across much of the state. In Schuylkill County, some fields 10% of trees have broken bud, but in smaller trees, the percentage is greater than 50%. If the small trees have southern exposure, they were close to 100%.
Douglas-fir Bud Break Beginning: Although the cold overnight temperatures seem to have held back the advancement of Douglas-fir bud break in many areas, a small amount of young trees had a few buds opening in southern York County last Friday. Warm temperatures over the weekend would have helped to push this along.
Today in northern York County, balsam twig aphid stem mothers were found on Canaan fir foliage. Balsam twig aphids are a pest of only true firs. Their feeding is what causes a twisting or kinking of a season’s new needles. The accepted growing degree day range for balsam twig aphid egg hatch is 30-100 GDD.
White Pine Weevil: This past Sunday in Schuylkill County, white pine weevils were found in several traps. These traps were in blocks of Eastern white pine and Serbian spruce. Soil temperatures collected that day (on the sunny sides of the trees) was exactly 50°F, proving that measuring soil temperature is a very effective method for predicting emergence.
Cold weather’s effect on insects? The question I have been asked the most thus far in 2014 is whether or not I think the cold temperatures we saw this winter have killed off the pests of Christmas trees. This winter was one of the colder winters in recent years and Pennsylvania saw some seriously cold temperatures, with several nights in negative numbers.
WHITE PINE WEEVIL: In parts of Pennsylvania today, trees and fields were once again covered with snow, albeit a light covering in South Central PA. Between the snow and cold temperatures, pest activity is getting off to a very slow start this season.
Although spring weather is taking its time showing up this year, the time to think about spring scouting activity is definitely here! This first scouting report of the 2014 Christmas tree growing season is your reminder that insects and mites will be active in your tree fields soon enough, so it’s time to be ready for them. This weekly scouting report will be published through the end of June to alert growers in Pennsylvania and the surrounding states to the current pest activity in Christmas tree fields.
SPRUCE SPIDER MITE: This week in Schuylkill and northern Dauphin County, spider mites have begun to hatch on arborvitae and juniper. In Schuylkill County, hatch approaches 50%, but in northern Dauphin, hatch is much lower at around 10%. The timing does fall in line with the expected GDD range for this pest: 50-121 GDD.
Temperatures have been steadily rising in Central PA and bud break has been increasing in all of the conifer species. Douglas-fir in Lancaster, Lebanon, York, Cumberland and Schuylkill County is pretty much at 100%. In Northern Dauphin, a small percentage of Douglas-fir trees (<5%) still have buds that haven’t broken. Spruces have also begun to break bud.