Home gardeners often find their evergreens turning brown at the bottom and fear that the lower branches of their trees are dead. A certain amount of browning and needle loss occurs in evergreens from winter injury and environmental stresses. Determining the cause of browning is the key to keeping your evergreens healthy throughout the year.
Evergreens include pine, cedar, cypress, spruce, juniper, arborvitae and true fir trees. These trees are well-known for their ability to remain green throughout most of the year. However, it's normal for some evergreens to turn brown and lose needles at certain times. Evergreens that have dead-looking lower branches require pruning to improve their health and appearance.
Winter injury is often a problem for evergreens. Trees that have suffered extensive damage from deep snow often have dead-looking lower branches. Winter causes food to become scarce for wildlife such as deer and rabbits, and these animals may feed on the lower branches of evergreens, stripping them of their needles and causing them to die or appear dead. Some needle diseases, such as Rhizosphaera needle cast, cause older needles on the lower branches of evergreens to change colors and die. Certain fungal diseases cause browning and death for the newest needles, which often proceeds to in the death of entire lower branches.
Evergreens require pruning each year to keep them healthy and vigorous. Regular pruning of dead lower branches is important to the health of the tree. Removing dead or diseased branches can help keep the tree structurally sound as well. When evergreen trees become very large, the lower portions can become shaded out by the crown and die as a result. Prune these lower branches away with clean, sharp pruning shears. Evergreens that are very large may require a professional tree-trimmer for best results.
Evergreens under attack from needle casts or fungal diseases may require chemical controls. Applying fungicides to evergreens with these conditions may help reduce symptoms and avoid further browning and dieback. Many local county or university extension offices accept samples for disease testing, which can help determine the best course of action.