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April 21, 2004

Christmas Tree Scouting Report -
Number 4

Welcome to the Christmas Tree Scouting Report for the week ending Wednesday April 21, 2004. The next report will be available after 5 PM on Wednesday April 28th. To receive a FAX of this week's message, please call (814) 865-1636. If you would like to receive this report via email, please send a request to rdlehman@state.pa.us and you will be added to the distribution list. Frequently, the email/fax report contains more information than we are able to fit into the 3-minute recording. To contribute observations to this report, please email to the address above or call 717 772-5229.

White pine weevil eggs were found in the terminals of white pine in Perry and York counties, and in Scotch pine in Carbon County. Growers should have applied their 1st spray to the top 1/3 of trees by now. With all the weevil activity seen this week on Norway spruce and Austrian, white and Scotch pine a second spray may be needed if this pest has been a problem in previous years. If you applied your sprays late this spring and eggs may have already been laid in the terminals you will want to check your fields for dying and dead terminals in June and prune out and burn any infested leaders.

Spruce spider mites are beginning to hatch in York County on Fraser fir. Some miticides require two sprays, 7-10 days apart, to achieve effective control. Miticides that interfere with chitin production are best applied when most of the overwintering eggs have hatched but before the adult stage has been reached. Some of the newer miticides can only be applied once a year and may require skipping a year before being used again. Check the label before applying any pesticide.

The control period for Cooley adelgids on blue spruce and Douglas fir is coming to an end. In Adams County this week the Cooley's were waxed over on blue spruce. On Douglas fir in Carbon and York counties the stem mothers had already deposited eggs under the cottony wax. Last week in Northumberland County the eastern spruce gall adelgids were covered in wax. After the stem mother is covered or eggs are present there is no benefit to be gained from chemical control. The next time for controlling these adelgids is in the fall.

Elongate hemlock scale was observed in York County but no crawler activity was found. We will continue to monitor this scale for crawler activity at a number of sites for the next few weeks.

It will soon be time to spray for Rhabdocline needle cast on Douglas fir. The buds of Douglas fir are beginning to swell and the bud scales are pealing back giving a lighter appearance to the buds. Trees planted on a southern exposure or near a macadam road tend to open earlier so you may want to keep an eye on these areas in the field. Fungicides used to control Rhabdocline needle cast are only going to protect the new growth, not kill the spores. It is important to have your spray in place before the fungus comes in contract with the new growth so, your first spray should be applied when 10% of the trees in the field are showing the first signs of bud break.

Stripped pine scale was found on Scotch pine in Carbon County. This is one of the soft scales which has the characteristic of producing a lot of waste material known has "honey dew", when feeding. Ants and wasps are attracted to the sugar content in the honeydew and are a good indicator of other sucking insect pests such as aphids, adelgid or scales on your trees. If you notice ants on or wasps flying around your trees take a closer look to see if you may have one of these pests. Trees often turn black due to sooty mold that builds up on the honeydew. This can also be a good scouting tip.

If you had damage from the balsam twig aphid on your true firs in previous years remember, control sprays are just before bud break and when all the over wintering aphids are hatched. An indication of balsam twig damage is twisted and stunted needle on last year's growth. The aphids can be seen with a hand lens on the under sides of last year's needles. They are pale green with a light waxy cast and a frequently a drop of honeydew on the tip of their abdomen. Also, the stem mothers can be seen on the opening buds.
The next report will be Wednesday April 28th after 5:00pm.