May 31, 2006
Christmas Tree Scouting Report Number 12 - May 31, 2006
Weekly newsletter compiled by Sandy Gardosik, PA Department of Agriculture.
Although eggs of cryptomeria scale are appearing beneath the female covering on Fraser fir in Berks, Dauphin and York counties, no eggs were found when scales were examined on Fraser and Canaan fir in Northampton County. To scout for this scale and its eggs, begin by examining the interior of the lower branches, toward the trunk of the tree. Look for chlorotic spots on top of the needles; if spots are found, examine undersides of the needles for scale. The male and female coverings are similar, resembling a tiny "sunny-side up" egg: the center is golden yellow with a milky-white ring. Eggs can be found by flipping over the scale cover with your fingernail or a pin and looking for golden yellow, oval eggs with a hand-lens. Additionally, you can dislodge the eggs by tapping an infested branch over a light-colored surface, where the eggs can easily be seen with a hand-lens. Once egg laying begins, crawler hatch follows in about two weeks. The best control is achieved when sprays are directed at the crawler stage. Scouting for crawler emergence will continue over the next couple weeks.
Rhabdocline was still obviously viable when lesions on Douglas fir were examined with a hand-lens in Dauphin and York counties. A quick test for Rhabdocline viability is to place a sprig with Rhabdocline in water, wait about ten minutes, and then examine lesions on the underside of needles. If the infected areas have swollen, and the epidermis is ruptured and appears orange, then the pathogen is viable.
Growers are asking if it is too late to spray for the balsam twig aphid (BTA) on true firs. Unfortunately, it is too late to avoid damage to the new growth. Also, spraying now would be detrimental to BTA's natural enemies such as lady beetles and syrphid flies. BTA is best controlled before the new buds open in the spring. By the end of June or by early July, this insect has completed its life cycle for the year, and will remain relatively protected in the egg stage until the following spring.
Bagworms are hatching in Berks and Dauphin counties. In Berks County about 85% of the eggs have hatched and the tiny young larvae can be seen on the needles. Good control can be achieved with one application of a registered insecticide if spraying is delayed for about two weeks after the first signs of egg hatch. This allows the majority of eggs to hatch and the larvae to exit the overwintering bag and be exposed to the chemical. Good control is achieved with the natural bacteria, Bacillus thringiensis (BT) if applied when larvae are small.
Spruce spider mites continue to be very active this year. A heavy spider mite population on Canaan fir in Northampton County has caused the previous year's needles to drop. If you sprayed for spider mites earlier this spring, you may want to re-scout your fields for mite activity and eggs to determine if additional control measures should be taken.
No eggs were found when adult striped pine scale was examined on Scotch pine in Dauphin County. Monitoring will continue over the next few weeks for eggs and crawlers.
Galls formed by the Cooley spruce gall adelgids on Colorado blue spruce and the eastern spruce gall adelgids on Norway spruce are beginning to develop and deform new growth. Look for purple-red colored galls on the tips of new shoots on Colorado blue spruce and green pineapple-shaped galls at the base of new shoots on Norway spruce. Remove galls by hand clipping, if possible, before late July. If galls are too numerous to hand clip, treat infested trees this fall or early next spring.
If you have any pest information to report please email Sandy Gardosik at email@example.com or call (717) 772-0521 and give pest, host plant and county where observation was made and I will include this information in the next report.