WASHINGTON — Are your evergreens turning yellow or brown? The symptoms could indicate a problem, but chances are they’re just part of the trees’ seasonal aging process. Close examination will reveal the cause – and whether any action is needed. Many healthy evergreens regularly experience yellowing and browning of older branch parts during autumn. The trees will drop affected needles later in the season. But if the symptoms present only on the innermost branches and on both the upper and lower sections of the tree, there’s probably nothing to worry about. It’s a normal part of the aging process. …If the yellowed branches are stunted, however, that could be indicative of a nitrogen deficiency. Similarly, if yellowed branch tips turn reddish-brown as the season progresses, the tree might have a potassium deficiency. …Some insect infestations may present similar symptoms, however, so close inspection is warranted, according to entomologist Dan Gilrein.