Many homeowners have expressed alarm over the yellowing of the inner needles on evergreens, particularly spruce. In some cases, most of the inner needles have turned yellow or brown, and the homeowner fears that the trees are diseased or insect-infested. If these symptoms fit trees in your yard, do not be alarmed, this is a natural condition called fall needle drop. The fact that needle drop appears to be earlier and more intense than normal this year can be related to drought stress. Evergreens do not keep their needles indefinitely. Older, inner needles discolor and drop off after one to 10 years, depending on the evergreen species. While a white pine may keep their needles for two to three years, a spruce may hold needles for seven years, and junipers may hold their needles for ten years or more. The intensity of the needle shed in the fall depends on the growing season the plant had when those needles were formed as well as the current growing season. We have gone through a very stressful growing season and the trees are shedding more of their older needles to minimize the number of needles that will need to be maintained. Although this phenomenon can be observed in pine trees, this year it is most evident in several species of spruce. Examine your trees to see just where the yellowing needles are found on the branches. If the current season’s needles on the tips of the branches are green, the condition is needle drop. If the needles on the ends of the branches are yellow, brown,or banded, there could be an insect or disease problem, possibly even severe drought stress. There is nothing you can do about fall needle drop. It is a natural process in the life cycle of evergreen trees. Because needle drops are more dramatic this year indicates that those trees are probably drought stressed and need water. It is very important that these trees receive regular watering until the ground freezes. Trees that go into the winter in a drought-stressed condition can be expected to suffer from winter injury due to desiccation. Apply water with a soaker hose, drip irrigation or a deep-root waterer, once a week. It is important that the soil be soaked to a depth of 6-8 inches.
