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June 1, 2005

Christmas Tree Scouting Report -
Number 10

Welcome to the Christmas Tree Scouting Report for the week ending May 11, 2005. The next report will be available after 5 PM on Wednesday, May 18. 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.

Minor frost damage was found in Dauphin, Lancaster and Northumberland counties this week. Most of the damage was found on both small and large Douglas fir. Other species lightly damaged were concolor fir and Norway spruce. Frost-killed new growth on Douglas fir was dry and brittle and very noticeable among healthy 3-4 inches of new growth. Trees that were just “stung” by frost had new growth that was stunted and twisted and the tips of the needles were brown. Growers probably remember the late frost that hit about the third week of May in 2002 that left many growers throughout the state wondering what amount of new growth they were going to have that year. Let’s hope we're in for some warm weather now that June is here.

Female cryptomeria scales are beginning to lay eggs underneath the scale covering on Fraser fir in Dauphin and Lancaster counties. These lemon colored eggs can be seen through the delicate covering of the female. If an infected branch is tapped over a white surface these eggs can be dislodged and viewed with a hand-lens. Last year at this time eggs were beginning to hatch, which reminds us that weather conditions vary from year to year and scouting can help time sprays more effectively then a calendar date. Monitoring for egg hatch will continue over the next couple weeks.

Another scale that was beginning to lay eggs at this time last year is the striped pine scale. This week there were no eggs found on Scotch pine in Lancaster County. This soft scale infests Scotch, Austrian and red pine. The female scale over winters and feeds on the bark of shoots and branches. One way to detect this scale is to look for black needles covered with sooty mold. This mold grows on honeydew, a waste product of the scale insects. It is very sweet and also attracts ants and stinging insects. Soft scale can be controlled with oil in late fall or early spring before scales become too large. The next opportunity to control this scale is when crawlers are present. This scale will be monitored till crawlers emerge.

Bagworm larvae are still emerging from the over wintering bags on blue spruce in Lancaster county. When some of the bags were torn open, eggs and young larvae were found. For best control wait till the majority of eggs have hatched and the young larvae are out on the needles before applying an insecticide. Bt, a biological insecticide works very well against this lepidopteron pest if applied when the larvae are small.

Elongate hemlock scale crawlers were found on the undersides of needles on Fraser fir in Lancaster County. These scales are found exclusively on the undersides of needles. Females are 1-3 mm long and somewhat narrow, transparent light-to medium-brown. Males are smaller, narrower, and powdery white. Look for chlorosis on the upper leaf surface and a dirty, whitewashed appearance due to the buildup of male scale coverings. Begin a spray program when scale crawlers are present at your location.

Spores of rhabdocline needlecast are still infectious in Dauphin County when the undersides of needles were examined in early morning, when dew was still on the trees. Most growers have applied their third spray for needlecast. Weather and spore viability will determine if a fourth spray will be needed two to three weeks after the third.

Growers with Swiss needlecast on Douglas fir will want to apply a fourth spray because this fungal disease sporulates longer.

Admes mites were found on Colorado blue spruce in Northumberland County. This mite has been found occasionally causing damage on spruce in Pennsylvania. Damage from Admes mite resembles spruce spider mite damage but Admes mite is larger and has a red body and long orange legs. We have been sampling for this mite over the last few years to learn more about the life history.

The next report will be out on Wednesday the 8th after 5:00pm.