Evergreens With Yellowing Needles in the Summer

Natural Process

• Dependent upon where on the evergreen needles are turning yellow, the condition could be a part of the natural aging process. Evergreens are referred to as such due to their habit of retaining needles for several years. Still, the needles do not last forever; once new growth has occurred at the tips of branches, more mature needles toward the center of the tree will turn yellow in the summer and fall away.

Time Frame

• This process normally appears on white pine needles toward the end of their second year of growth, while red pine needles often literally hang on until their fourth or fifth season of growth before turning yellow. The species of evergreen, in addition to weather conditions, plays a role in how quickly needles will begin to yellow. If the tree has suffered from drought, a change in the color of needles will be quicker and more noticeable.

Prevention/Solution

• The best way to ensure that disease is not responsible for evergreens with yellowing needles in the summer is to inspect new bud growth at the tips of branches. If they are fat, green and covered with a collection of white or green scales, the yellowing on the interior needles is likely normal. To ensure that a dry summer does not prematurely yellow the needles, a drenching supply of water should be applied to the tree in November before it enters dormancy.

Environment

• Environment and cultural stresses are a significant contributor to the premature yellowing of evergreen needles. Excessively wet soil that continues for a significant period of time contributes to root decline, a condition that deprives the tree of nutrition and water, leading to a yellowing and browning of needles. Evergreen plants also lose water from their needles during the winter. Salt spray from de-icing solutions, as well as the presence of excessive sodium in the earth, causes evergreens to prematurely yellow.