Question
Aspen-Cotton-1
I just noticed my 6" cal. Aspen has a white, cottony substance all over it's bark, from the bottom of the trunk to the second tier of branches, about 12' above ground. It is actually "dripping" off in places. I do not see insects and have never heard of this type of event. The Aspen looked greener than ever all summer. It's now Oct. 5. The tree is at about 6,000ft., in the foothills of the Sandia Mtns., 15 miles north of Albuquerque. Do you know what this might be? I will attach a photo. Thank you! M. Knudsen, Placitas, NM
AnswerLooks like one of the sucking type insects--aphids or scale. The Oystershell Scale secretes a waxy substance and the wooly aphids do also. Scales are like a small turtle and do not move--check and see if there is a hump under the waxy stuff. If it is then this is a scale insect. If there is no hump and the waxy material moves when touched (the insect may have completed its life cycle and gone leaving the waxy stuff) if it moves then these are aphids.
Either way the controls are similar.
I lean toward the scale.
Aspen is very susceptible to infestation by the oystershell scale. Heavy infestations of the oystershell scale reduce tree vigor because the scales suck water and nutrients from the tree. These insects sometimes kill limbs or entire trees. Eggs overwinter under their mother scale on the bark of trees. Crawlers hatch in late spring and settle on the bark, usually 2-3 weeks after apple bloom. They insert their mouthparts and then form a waxy coating over their bodies. As they grow, they assume an oystershell-like shape, becoming elongate with one end enlarged. The gray scales mature late in the summer, and at that time, the females lay eggs under their waxy covers. A dormant application of horticultural oil will control overwintering scales.
The city of Albuquerque has a city Forester and he might be able to advise on what to do to treat this insect. Nick Kuhn can be reached at City Hall in the Environmental Health Department at 505-768-2706.
