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April 25, 2003

Christmas Tree Scouting Report -
Number 5

Welcome to the Christmas Tree Scouting Report for the week ending April 25. The next report will be available after 4 PM on Friday May 2. To receive a FAX of this week's message, please call (814) 865-1636. To report pest activity at your location or request the email report, please call 717 772-5229. 

This week in Adams, Allegheny, Perry and York counties, overwintering eggs of the spruce spider mite are hatching. At the sites visited in Perry and York counties about 50% of the eggs had hatched but in Adams, hatch was just beginning. A Perry County grower noted hatch on his southern facing slopes only. Newly emerged larvae are light salmon or pale red, hairy, and only have 3 pairs of legs. After feeding, the mites turn dark green or red. These mites can be seen with a 15x hand lens at the base of the needles. Tapping infected branches over a white paper plate will dislodge these mites and make viewing easier.

Some miticides require two applications, 7 to 10 days apart, to control active populations. Miticides that interfere with chitin production are best applied when most of the mites are hatched but before adult stages are reached. These newer miticides have label restrictions on the number of applications per year. Check the label on your material before applying.

The time is nearing for Rhabdocline needle cast control. This week at some sites in Adams, Perry and York counties a few Douglas fir buds had broken. In Dauphin County, buds were swollen and light green but there were no sign of infectious spores. When spores are mature, the brownish areas on the needles appear puffy. This area splits open on the underside of the needle and orange spores can be seem with the aid of a hand lens. You can force this process by placing suspect needles in warm water for a short time. The excess moisture, mimicking spring rain and heavy dew, will cause the infected areas to swell and break open, revealing the spores. Since infectious period starts at or shortly after bud break, and control materials work to protect new growth from being exposed to the fungus, sprays should be made when 10% of the trees at the location have broken bud. This bud break based timing can vary tremendously from place to place and even within any grower's fields.

Southern exposures and certain provenances are more likely to break bud early. In order to get good control, a second and third fungicide spray must be applied to assure continued protection for emerging new growth. The second application should occur one week after the first, and the third application, two weeks after the second. In cool springs, when new growth hardens slowly, a fourth spray may be required.

The spring control period for Cooley spruce gall adelgid has ended. Eggs were found underneath the stem mothers in Adams, Perry and York counties. In Westmoreland County, the nymphs are completely covered with waxy threads, making control impossible. The next chemical control opportunity will be in the fall.

At our white pine weevil trapping site in Perry County, eggs are increasing in numbers but no larvae have been found. Mike Masiuk, Allegheny County Cooperative Extension, reports finding eggs in southwestern counties, but no larvae to date.

No crawlers of elongate hemlock scale were found on Fraser firs in Adams County this week. The thousands of other specimens examined were all females. We will continue to monitor for crawlers in the coming weeks.

Adult moths, suspected of being Eastern pine shoot borer, were collected in Scotch pine fields in Dauphin and Perry counties. We are cooperating with producers to test pheromone formulations for this pest. In 2002, our traps did not yield any adults but we suspect we deployed them after adult flight. If the lures are successful, we hope to also trap for the species of Eucosma that has been found boring in Fraser fir shoots during the last several years.

In Allegheny and Westmoreland counties, European pine sawfly eggs have hatched and the 3/8-inch larvae are consuming needles on Scotch pines. Also in that area, pine spittlebugs eggs have hatched and small spittle masses can be seen on the trees. This pest is particularly important for growers troubled with Sphaeropsis tip blight. Control of spittlebugs must wait until adults emerge in late summer while the sawfly larvae are easily controlled at this time of year.

The 2003 list of insecticides and miticides labeled for use in Christmas tree plantations has been completed. If you wish to receive a copy, please call 717 772-5229 and a copy will be forwarded to you. Email recipients of this message will receive a copy automatically and the list will appear in the PCTGA bulletin in the near future.

Traps for the recently detected Douglas fir needle midge have not contained any adult midges to date. We are monitoring sites in Lehigh and Northumberland counties to define the control period for this pest.

The next report will be available after 4 pm on Friday, May 2.