June 6, 2003

Christmas Tree Scouting Report -
Number 11

Welcome to the Christmas Tree Scouting Report for the week ending June 6. The next report will be available after 4 PM on Friday June 13. To receive a FAX of this week's message, please call (814) 865-1636. To report pest activity at your location or request email report, please call 717 772-5229. For local Growing Degree Day information, please go to and click on Crop Weather along the left margin.

For those growers expecting an email version of this report, our email has been temporarily disabled and the reports will not be sent until Monday, June 9.

Pine needle scale crawlers are out on needles in Dauphin County. A few crawlers were also active on the needles in York County earlier this week. This is the optimum time to control the first generation of this armored scale pest of conifers. On Scotch pine, this scale can be extremely abundant, making some trees look like they are flocked. On eastern white pine, the scale does not reach these epidemic proportions. Good control of this first generation may make it unnecessary to apply chemicals against the second generation. Two applications of a registered insecticide, about seven days apart, are required. Thorough coverage is important, also.

Another serious armored scale pest of conifers, known as cryptomeria scale, is being monitored in Berks, Dauphin, Lebanon and York counties. In York County, a few of the lemon yellow eggs were found under the female scale covering earlier in the week. The Dauphin County population is also starting to produce eggs but no eggs were present in Berks or Lebanon county samples. This scale occurs on the underside of the needles and can be very damaging, especially on true firs. Symptoms include yellow areas on the upper side of needles and unthrifty trees, especially on bottom branches.

Bagworm eggs have not hatched at our monitoring site. This pest becomes active later than most people realize. This delayed hatch may produce a false sense of security for some growers who may think the pest did not survive the winter. However, by late June or early July, the small "walking" bags will be visible and by August, serious defoliation can occur. Controls are best applied against young larvae and one of the most effective controls is Bt, a biological insecticide.

Spruce spider mites are active in Adams County but some growers may not experience significant populations this spring. The frequent and heavy rains that we have had this year will often affect spider mite populations by simply knocking the mites from the trees. But, don't be fooled by this pest, either. Keep monitoring populations since they seem to have the ability to explode almost overnight.

Rhabdocline sporulation is continuing at some locations and many growers have needed to apply their 4th spray due to the prolonged, wet spring. To determine if it is safe to discontinue your protective fungicide applications to your Douglas-fir, you must examine some of the fruiting structures on last year's needles. If they appear dark brown or black, especially on a damp day, sporulation has ended. If the fruiting body on the underside of the needle is still reddish-brown to orange, spores are still present and protection is needed. Another method of checking the sporulation is to drop the needles into warm water for a period of time. This forces the fruiting structures to open and reveal the spores - or, hopefully, the lack of spores.

The next report will be available after 4 pm on Friday June 13.