June 2, 2004
Christmas Tree Scouting Report -
Welcome to the Christmas Tree Scouting Report for the week ending Wednesday June 2, 2004. The next report will be available after 5 PM on Wednesday June 9th. To receive a FAX of this week's message, please call (814) 865-1636. To contribute observations to this report, please email to the address above or call (717) 772-5229.
There are still viable spores of Rhabdocline needle cast on the needles of Douglas fir in Adams, Chester, Franklin, Lebanon, and York counties. An easy way to test for viability of this fungus is to remove some infected twigs and place them in some warm water, or a puddle in the field, for about 10 minutes. Examine the infected areas of the undersides of needles and look for swollen areas that are split open and colored orange. These are signs of active fungus spores. Areas that are black and shrunken have completed there life cycle for the growing season and cannot create new infection. These needles will drop from the tree in the next few weeks. A hand lens can help in evaluating your situation. Depending on your Rhabdocline evaluation and the timing of your last spray you can decide if a fourth spray will be necessary.
The eggs of Cryptomeria scale are beginning to hatch on Concolor fir in Chester and Franklin counties. Crawlers were also found hatching on Fraser fir in Franklin and York counties. No eggs were hatched in Lebanon County this week. Look for lemon yellow crawlers on the bottom of infested needles of previous years. As more eggs hatch the crawlers will be visible on the bottom of this year's needles. The best time to spray for this scale is when the crawlers are active and before they settle and begin secreting a protective cover. Because the eggs hatch over a couple weeks a second spray with a registered insecticide will be needed.
Striped pine scale eggs are beginning to hatch on Scotch pine in Adams County. However, the majority of crawlers are still under the adult females. In the next few days the pinkish male crawlers will be visible on the needles while the tan female crawlers will remain on the bark of twigs. Since soft scales do not produce a protective cover soon after they settle, as do the armor scales, growers can wait till all eggs are hatched and crawlers are out on the plant and well exposed before applying their spray.
Bagworm larvae have been active in Lancaster and Perry Counties for the last couple weeks and are still small enough to control with microbials such as BT, (Bacillus thuringiensis). This bacteria is very effective on young larvae but will not control more mature bagworms. Waiting till larvae are big will call for harsher insecticides and control may not be as effective while damage will be more severe.
The larvae of white pine weevil were found
at the base of terminals but still above the first whorl of branches
on white pine and Douglas fir in Adams County. These mature larvae
are beginning to construct "chip cocoons". When larvae
mature they begin to chew into the pith of the tree constructing
a cavity where they cover themselves with fine wood chips. Here
they will pupate and transform into adults which will emerge later
in the season. Now is the time to walk your fields and look for
dying terminals in all species of Christmas trees. Cut out any damaged
terminals down into the healthy wood and remove the infested material
from the field. Mature larvae are able to complete development in
these cuttings so they should be destroyed by burning, if possible.
The sooner this is done the less damage there will be to the tree.
You will also help curb the weevil population for next year.
I'm still seeing building populations of spruce spider mites at many farms. Growers who were planning on using Savey this year but have not sprayed yet may want to save this costly material for next year. Savey is a chitin inhibitor and will not have an effect on mature mites. It is best applied when populations are building, especially in spring after egg hatch. At this time of year, with populations already relatively high, it is necessary to include a quick knock down miticide in a tank mix with Savey. This will prevent severe damage and protect the trees for the remainder of the season but does add to the cost of miticide application. Remember to rotate classes of insecticides and miticides to prevent resistance.