October 4, 2006
The term "evergreen" used to describe conifer trees isn't exactly accurate. It's normal for some of the needles on evergreens to turn yellow or brown and fall from the tree in autumn. This seasonal needle loss, also called fall needle drop, is a natural occurrence. The oldest (innermost) needles are eventually shed from trees such as pine, spruce, and fir. The discoloration and loss of needles can be alarming to tree owners that are not aware of this normal process. Some fear that a disease is rapidly occurring.
One of the more interesting "conversation pieces" to keep in an extension office, natural history museum or home is the nest of the baldfaced hornet. The baldfaced hornet is a social wasp found in the familiar large, gray, paper nests attached to a tree branch, shrub, utility pole or house. The paper-like nests are made of chewed wood fiber mixed with saliva.
Samples with the following problems have been seen in the Plant Disease Clinic recently:
Iron chlorosis on pin oak and river birch
Marssonina leaf spot on aspen