April 12, 2006

Christmas Tree Scouting Report Number 5 - April 12, 2006
Weekly newsletter compiled by Sandy Gardosik, PA Department of Agriculture

Eggs of the white pine weevil adult have been found in the leaders of white pine in Lebanon and York counties. Weevils are still being found in traps in Columbia, Juniata, Lebanon, Perry and Schuylkill counties. To scout for the eggs look for feeding damage on the main leader With your fingernail or pocketknife carefully slice a thin layer of bark away from over the feeding hole. Be careful not to cut too deep. One to five creamy, jellybean shaped eggs about 1mm in length can be found in one hole. Many growers have applied their second spray for the control of the white pine weevil.

Spruce spider mite eggs are beginning to hatch on Fraser and Canaan fir in Adams, Dauphin, Lebanon, and York counties. Spruce spider mites are considered a "cool season" mite so populations are highest in spring and fall. Several generations may be produced in a single season. A single generation from egg to adult can be complete within 15 to 23 days depending on temperature. In mid summer, when daily temperatures consistently exceed the mid-80's, spruce spider mite populations decline. When eggs first hatch they are a salmon to light red color, after feeding the mites turn a dark green or dark red. After spring hatch, the mites feed on old growth for several generations until new growth hardens off. Because of old growth feeding early in the season, sprays need to reach the interior of the tree. If good control is achieved in early spring, damage from previous years can be covered by new growth. To check for egg hatch, take a white sheet of paper and tap branches over sheet, wait a few seconds for mites to upright themselves then with handlens look for moving red mites. Control mites with a registered insecticide or miticide followed by a second spray application 7 to 10 days later unless label states otherwise.

Now is a good time to scout for spruce needle rust on Colorado blue spruce and Serbian spruce. Look for yellow to orange bands on last year's (2005) needles. This needle rust was first detected in 1991 in Luzerne County and has now been found in most eastern PA counties. Management tactics will be similar to Rhabdocline needle cast. Fungicide applications will begin at bud break. Follow the label directions.

Early spring control for Cooley spruce gall adelgids on Colorado blue spruce and Douglas fir and eastern spruce gall adelgids on Norway spruce is nearing and end. Most female adelgids are covered with a white "wool" of wax and eggs are beginning to be laid under the female. Control is best achieved before a thick layer of wax is produced and eggs are laid.

If you have any pest information to report please email or phone Sandy Gardosik at  or (717) 772-0521 and give pest, host plant and county where observation was made and I will include this information in the next report.