March 28, 2003
Christmas Tree Scouting Report -
Welcome to the first Christmas Tree Scouting Report of the 2003 season. A new report detailing insect, mite and disease situations from the previous week will be prepared every Friday. The next report will be out after 4:00 pm Friday April 4th. To receive a FAX copy of this report, please call 814 865-1636.
You can contribute to these reports by calling Sandy Gardosik at 717 772-0521 or Rayanne Lehman at 717 772-5229. Please leave a message with details such as pest name and stage, type of host tree, county location, date and what was happening. Your name and telephone number would be useful if we have any questions. For those of you receiving email reports, you can also send scouting observations by email.
Although the winter of 2002-2003 included a lot of snow and colder temperatures than we have endured for a few years, you can rest assured that the insect pests did not freeze out. Spring is here, on schedule, and accumulated growing degree-days indicate we are about where we should be at this time of year. So start your pest scouting and if you can get into the fields, controls are needed.
White pine weevils are out and feeding on the terminals of white pine in Lancaster, Northumberland, Perry, and Snyder counties. This is one of the first major pests of Christmas trees to become active in early spring, with the onset of warming temperatures. Now is the time to scout those fields that have had a history of white pine weevil infestation. On warm, sunny afternoons you may catch sight of weevils feeding on the terminals of host trees. Or you can look for feeding wounds in the bark, particularly on eastern white pine. These pinhole sized feeding wounds will be oozing with clear sap. Some trees may be too tall to examine and this is when weevil detection traps can come in handy. Weevils were in our traps in Lancaster and Perry counties this week and we received word that a Maryland grower trapped several weevils at the end of last week. To control this weevil, a registered material should be applied to the top 1/3 of trees. Growers can begin making those applications in areas where weevils are active.
Another important pest that is active in early Spring is the Pales weevil. Fresh feeding damage from overwintering Pales weevils was detected this week on lateral branches of healthy Scotch pine in Northumberland Co. Live, overwintering weevils were found just below the surface of the debris around Scotch pine stumps cut during the 2002 harvest in Perry and Northumberland counties. Adult weevils will feed on the bark of healthy conifers for several weeks before laying eggs in bark or exposed roots of fresh stumps or dying trees. Scotch pine is the preferred host for breeding populations of Pales weevil but adults will readily feed on all conifers. Cull piles of fresh cut Scotch are also good breeding grounds and should be burned or chipped. Now is the time to treat individual scotch pine stumps from the previous seasons harvest with a registered insecticide will help to control Pales weevil.
Eriophyid mite eggs have started to hatch and immatures were found on Norway and blue spruce in York County. This mite, referred to as spruce rust mite, is a cool season pest. It is very small, which means a 15-20x hand lens is necessary for detection of this wormlike mite. Overwintering eggs, found on the undersides of the needles, are about the size of the white spots, or stomata, on the needle. Damage from these mites is usually a grower's first sign of an infestation. Spruce rust mite populations can rapidly build to damaging levels and cause bronzing to the needles on Norway and a silvering to the needles on blues. Dormant oil works well on eriophyid mites but remember the bloom will be removed from Colorado spruce, causing bluish needles to revert to green. New growth that comes out after spraying will again have that nice blue color. Not all general miticides are labeled for eriophyids so be sure to check the label for eriophyid or rust mites before spraying.
In Perry, Northumberland, Snyder, Dauphin and York counties, overwintering nymphs of Cooley spruce gall adelgids can be found on the under sides of Douglas fir needles. These adelgids cause chlorosis and needle distortion on Douglas fir. On Colorado spruce, galls form on new growth due to this adelgid. At this time the nymphs are just beginning to produce wax around the edge of their body. If you have had problems with this pest and did not spray last fall, here is your chance. Once this insect covers its body entirely with those white waxy strands, control is no longer feasible. This is also the same management practice to follow with Eastern spruce gall adelgid on Norway spruce
Now is a good time of the year to do some pre-season scouting for insect and disease problems. Many pests are easier to spot before the new growth starts. Cultural and mechanical control can also be used to eliminate some pests at this time of year. Scotch pines infected with pine-pine gall or harboring initial infestations of striped pine scale can safely be cut out and destroyed now. In all pines, the white, elongate bodies of pine needle scale are easy to detect at this time of the year. Symptoms of rhabdocline are evident on Douglas fir since infected trees have distinct red-brown blotches on the needles at this time of year. On all conifers, the bags from last years' bagworm are easily detected. Removal of bags containing overwintering eggs will go a long way to keep the population down this year. Taking time to scout now will be worth the effort in May and June.
And remember all insects are not bad. There were a lot of lady beetles out on the trees this week. The lady beetles are emerging from their overwintering sites and are looking for some bad bugs, like aphids and scales, to feast on.
The next report will be available on Friday, April 4 after 4 pm.