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April 20, 2005

Christmas Tree Scouting Report -
Number 4

Welcome to the Christmas Tree Scouting Report for the week ending April 20, 2005. The next report will be available after 5 PM on Wednesday, April 27. To receive a FAX of this week’s message, please call (814) 865-1636. If you have pest activity to report, or would like to receive this report by e-mail, please leave a message at 717 772-0521 or e-mail sgardosik@state.pa.us and your name will be added to the distribution list.

Spruce spider mites are beginning to hatch on Fraser and Canaan fir in Dauphin and Lancaster Counties. Growers should begin scouting their own trees to determine if the overwintering eggs are beginning to hatch and a registered miticide is needed. To scout for mite damage look for the yellow to brown discoloration at the base of last years needles.

It will soon be time to spray for Rhabdocline needle cast on Douglas fir. In Bucks, Dauphin and Lancaster counties a few buds could be found throughout the field that were just beginning to show green tips of new needles. The infected reddish-brown areas on the undersides of needles are beginning to swell. You can determine how close Rhabdocline is to maturity by placing an infected twig in warm water and waiting about 10 minutes to examine the undersides of needles with a hand lens. If the spores are close to mature the needle surface will split and expose orange colored fruiting bodies.

Another pest specific to Douglas fir is the Douglas fir needle midge. Since first found established in Pennsylvania Christmas tree plantations in the summer of 2002, our survey to present has nineteen counties recorded on record. All counties in the southeast corner of the state have been found infested with the midge and extends as far north as Lycoming county and as far west as Perry county. Bucks and Lehigh counties seem to be more heavily infested with this pest to where spray treatments have been needed. These fragile flies, measure only 3mm long with orange abdomens and begin to emerge as the buds of Douglas fir break. Within a few days after emergence, mating takes place and the females begin laying eggs on the new expanding needles and under the bud scales. Eggs hatch within a few days and enter the needles immediately. Once larvae enter needles control is not possible. Chemical controls need to be in place before females lay eggs. We will be monitoring for emergence in Bucks, Schuylkill and York counties.

Male and female cones are beginning to form on Douglas fir in Bucks, and Dauphin Counties. Female cones are larger and higher on the tree and stand upright on the branches and have a pink-purple color. Male cones are found lower on the branches and hang downward and are smaller and normally more plentiful on the tree.

One of the soft scales known as striped pine scale was found on Scotch pine in Lancaster County. One good way to scout for this pest is to look for black needles covered with black sooty mold. This mold grows on the honeydew that is being secreted as a waste product of the scale. Ants and wasps are also attracted to this sweet material and can be another indicator of the presence of soft scale. Spraying with oil now when scales are small can be an effective control. Once scales get closer to maturity their bodies become tougher and oil is not as effective. The next window of opportunity is when crawlers begin to hatch.

The next scouting report will be Wednesday the 27 th after 5:00pm.