The Plant Disease Clinic has been receiving evergreen samplesshowing seasonal needle loss. (Many people panic at this time ofyear when they notice needles yellowing and falling from theirtrees.) Fear not, evergreens do not keep their needles forever. The older, inner needles eventually turn yellow or brown and fallfrom the tree.
White pines show the most noticeable needle drop. Usuallyonly one year's needles remain attached by November. Scots andAustrian pines generally retain their needles for three years. Needle drop is often not very noticeable on spruce and fir. On theother hand, arborvitae and some cedar needles turn brown ratherthan yellow with age and the change is quite noticeable.
Patterns of needle drop vary from year to year and from treeto tree. Adverse conditions in the summer and fall may lead tomore pronounced needle drop.
This article originally appeared in the September 16, 1994 issue, p. 139.