What Is Making Evergreen Trees Turn Brown?

Natural Causes

• As trees age, some browning occurs. Leaves and needles may live three to six years and then turn brown before dropping and making way for new growth. These needles and leaves are typically found inside, closer to the tree trunk where they may not be noticed. Since this browning is natural and harmless to the tree, no action is needed.

Weather

• Browning due to drought usually occurs in late summer or early autumn. It starts at the treetop and works downward. Browning can also be caused by strong, dry winds and temperatures that get close to freezing in winter. Making sure trees are watered and protected from too much sun and wind helps prevent browning.

External Causes

• Some soils have high salt levels that can damage trees and cause browning. Watering can help, but salty soil may not be suitable for evergreens. Mites, aphids and other sucking insects pull sap from trees. When many insects are pulling sap, it causes leaves or needles to turn brown and die. Browning can also be caused by herbicides that harm new tree growth. Herbicides and insecticides should be chosen and applied carefully to avoid tree damage.