June 27, 2003
Christmas Tree Scouting Report -
Welcome to the Christmas Tree
Scouting Report for the week ending June 27. To receive a FAX of
this week's message, please call (814) 865-1636. This is the last
regular message of the 2003 scouting season. This service was initiated
in 1994 and with this week's report, we are closing our 10th
season. We intend to resume this service in late March of 2004. For those
of you receiving the email reports, your report will come to you automatically. For those growers using the 800 number or Fax, please check after 5 PM on March 26, 2004 for the report.
Cryptomeria scale, an armored pest of true firs and other conifers, is now in the crawler stage at sites in Lancaster and Lebanon counties. Crawlers were reported to be active in Dauphin and York counties last week. The crawler stage for all scale insects is the easiest stage to control. For armored scales, it is the best opportunity to reduce populations since all other stages are well protected under their waxy coverings.
Scale crawlers are only mobile for up to 24 hours. After that time, the fragile, unprotected crawler must settle and begin to feed, or risk dying on the needles. Once a scale inserts the long mouthparts and begins to feed, it will spend the remainder of its life at that site. Occasionally, crawlers will settle under the covering of the female, resulting in layers of scales. This makes control all but impossible.
Control applications for Cryptomeria scale should be started as soon as the yellow crawlers are spotted and continue every 7 to 10 days until no new crawlers are found. Because this pest occurs on the undersides of needles, thorough coverage is required. Growers who control weeds in the rows and butt-prune trees report better success than those who do not follow these practices.
Douglas fir needle midge eggs have hatched at a site in Lehigh County. The minute, colorless larvae are feeding inside the maturing needles. Symptoms are very subtle but infested needles are slightly bent and paler in the area where the larva is feeding. Chemical controls at this time are not practical. We are still looking for Douglas fir growers in Lehigh and Northampton counties that suspect they may have this pest. Please call Rayanne at (717) 772-5229 if you think you have Douglas fir needle midge at your site. Surveys for this newly detected pest will be conducted this summer to delineate the distribution in Pennsylvania.
Crawlers of stripped pine scale were active on Scotch pine in Carbon County this week. This soft scale is restricted to pines and feeds mostly on the bark, as opposed to the needle feeding of most other conifer scales. Crawlers are light tan when they emerge from the helmet-shaped female covering. They are easy to spot on the bark and needles. Those few settling on the needles will be males; females are restricted to bark feeding. As a result of their feeding, females produce honeydew. This sweet liquid quickly becomes infected with sooty mold and it is common to find trees heavily infested with stripped pine scale that are literally blackened with the sooty mold growth. This scale can be controlled with dormant applications of oil, but crawler sprays are also effective.
We continue to receive reports of dead tips on Douglas fir trees. This is damage from gray-mold, as reported several weeks ago. If you look closely at the damaged area, you may be able to see the light-colored mycelia. These thread-like structures will not be present if Sphaeropsis or frost causes the damage. Our cool, wet spring is to blame for the damage and shearing should remove the dead tips.
Thank you for you support for our scouting report. We look forward to starting our 11th year in 2004.