April 14, 2004
Christmas Tree Scouting Report -
Welcome to the Christmas Tree Scouting Report for the week ending Wednesday April 14, 2004. The next report will be available after 5 PM on Wednesday April 21st. 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 firstname.lastname@example.org 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.
This week in York County, Pales weevil damage was evident on white pine and Douglas fir. These weevils will also cause damage on true firs and spruce. The adults feed on the bark of shoots and small branches causing shoot tips to die. This is also known as "flagging". If your noticing shoot tips beginning to brown, follow the twig back and you may find an irregular patch of fresh feeding at the twig base, on the under side of the dead shoot. These weevils have reddish brown to black bodies with a prominent snout and measure about 1/3 of an inch long. The adults feed on the branches on warm nights and hide around fresh cut stumps and leaf litter during the day. Adults prefer fresh cut scotch pine stumps for breeding but if feeding damage is heavy and weevils are also being found around white pine stumps, spraying with a registered stump spray now will help control this weevil.
Conditions for Rhabdocline needlecast were ideal in 2003 and weather conditions made it difficult to apply sprays at a timely manner. At this time of year, the reddish-brown symptoms and needle loss can be quite noticeable in a Douglas fir field, even from a distance. Up close, these needles show reddish-brown bands on both the upper and lower surfaces of infected needles. Closer to bud break the undersides of the infected needle will swell and rupture exposing the infectious spores. It is these spores that re-infect the new expanding needles. Another needlecast of Douglas fir that is showing up more frequently this year than in previous years is Swiss needlecast. This is also probably due to the wet weather during the sporulation period in 2003. Symptoms of Swiss needlecast are different than Rhabdocline; needles infected with Swiss show gradual yellowing or mottling and browning of the needle tips on first, second or third year needles during the winter months or in the early spring. Examination of the undersides of these needles with a hand lens will reveal rows of minute, round, black fruiting bodies on each side of the midrib of the needle. Needles infected with Swiss needlecast remain on the tree longer then those infected with Rhabdocline but both needlecasts only affect the current year needles. The spray program for Swiss needle cast begins between the second and third spray for Rhabdocline needle cast. So, since Swiss needlecast sporulates longer than Rhabdocline, including a fourth spray in your control program on Douglas fir can combines the control programs and will provide control of both diseases.
Elongate hemlock scale was found on Frasier fir and Douglas fir in Northumberland counties but no crawlers were found. This scale can also be found on spruces. This scale is an armored scale with multiple overlapping generations making control difficult. Contact sprays against crawler's gives best results however; multiple sprays are needed throughout the growing season.
Spruce spider mite eggs were found in York County but no eggs were hatched. An early dormant oil spray can be applied at this time to control the overwinter eggs. Remember, if dormant oil is used on Colorado Blues, the blue bloom will be removed and will not return till the new growth comes out.
The overwintering eggs of the Balsam twig aphids are hatching in York County on Frasier fir. Stem mothers are busy feeding and maturing on last year's growth. The control period for this aphid is right before bud break when most of the overwintering eggs are hatched and before live young are laid.
The next report will be after 5:00 pm on Wednesday the 21st.