The critical factor is the age of the affected needle. However, we have been receiving calls from people concerned about excessive needle loss on spruce. Generally this is due to a combination of normal interior needle drop and the loss of current and one-year old needles from rhizosphaera needlecast disease. Usually the interior needles merely turn yellow before falling, the needles infected with needlecast turn a purplish-red before falling. There is no recommended control of needlecast at this time of year.
Control is initiated in the spring just as the new growth begins.
At this time we start getting questions on the use of anti-transpirants. Anti-transpirants are chemicals designed to reduce transpiration. They are primarily used in the winter months to protect conifers from winter-burn. Evergreen exposed to windy, sunny winter conditions can lose water from the foliage. This water can not be replaced as the stem and soil are frozen or very cold.