May 24, 2006

Christmas Tree Scouting Report Number 11 - May 24, 2006
Weekly newsletter compiled by Sandy Gardosik, PA Department of Agriculture.

Rhabdocline needle cast fruiting bodies were still viable when the undersides of needles with brown lesions were examined with a hand lens in Adams, Dauphin and York counties. Early June may be the time to determine if a fourth spray will be necessary.  If infectious areas on the undersides of needles are no longer swollen, but dry and bright orange spores are not visible, the infection period has come to an end.

Bagworms are beginning to hatch on Colorado blue spruce in Lancaster County this week. No hatch was found on Canaan fir in Dauphin County or Colorado blue spruce in Lebanon County.  Inside each bag that housed a female moth the previous year, are several hundred overwintered eggs. These eggs begin to hatch within the bags in late May in the southern counties and early June in the more northern regions. Tiny caterpillars about 2mm long with shiny black head capsules emerge from the base of the bag on a silken thread they secrete. The newly hatched caterpillars construct a protective covering with host material and silky threads it secretes which the caterpillar will continue to enlarge as it grows. When the larvae are young they feed on only the needle surface; as they grow, whole needles are consumed causing defoliation. By late July-August, larvae are full-grown, and will securely fasten their bag to a branch with silk and pupation takes place inside the bag. The male emerges as a true moth and flies to bags containing the worm-like females and mates before dying. Before she dies, eggs are deposited within her pupal case where they overwinter to start a new generation the following spring. Control is best achieved when sprays are applied to young larvae. Waiting a week or so to allow all young caterpillars to emerge from the overwintering bags will control this pest with one application of a registered insecticide.

Pine-Pine gall rust is sporulating on Scotch pine in Dauphin County. Look for bright orange spores on the galls. The best control method is to remove galls from trees before they produce spores that can infect other Scotch pines in the plantation.

No eggs of Cryptomeria scale were found under the female covering this week in Lebanon and York counties. I expect egg laying to begin in the next week.

Another scale that I expect will be laying eggs on Scotch pine in the next week or so is the striped pine scale. This scale is related to the pine tortoise scale, not commonly found in Pennsylvania. These two scales are impossible to differentiate since they have similar characteristics. However, controls are the same for life stages of each scale. Apply insecticide when crawlers are present.

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