The Characteristics of Dying & Rotting Pine Trees

Appearance of Rapidly Dying Pines

• Rapidly dying pine trees are likely to display thinning foliage, stunted growth and discolored needles. They also may show signs of wilting, browning or yellowing before a rapid onset of death. Another important indicator of quickly dying pines is the presence of conks in the litter at the base of the trunk. Conks are wood rot fungi, similar to mushrooms, and have a bracketlike appearance.

Common Causes of Rapidly Dying Pines

• Annosus root and butt rot is the most common disease for pines and affects the foliage, resulting in a reddish needle color. It also gives trunks and roots a red-brown stain, causing roots to rot. Affected trees may blow down while still alive. The disease kills pines in a matter of a few months.

  Wilted, yellow or browning pine trees may be infected by the pine wood nematode (Bursaphelenchus xylophilus), which results in death within one month to 90 days. Nematodes are carried to the trees by pine sawyer beetles (Monochamus spp.). Those parasites feed on plant cells surrounding resin ducts, causing air pockets that stop the trees from moving water upward.

Signs of Slowly Dying Pines

• Older trees developing yellowing needles and producing numerous small cones may suffer from Littleleaf disease, leading to gradual decline and death. Developing galls and swollen areas on trunks or branches can be signs of rust disease, if it spreads into a tree, then death is the likely result. Heavy pitch flow down tree trunks can be a sign of pitch canker, when may result in trunk infections and cause the trees' death.

Benefits of Decaying and Rotting Wood

• Dead and dying native pine trees in a forest setting are important to wildlife because decaying and rotting wood forms a major part of forest life, particularly nutrient cycling. Studies in the Pacific Northwest confirm there is more life in a dead tree than a living one. The bole of a living tree contains about 5 percent living cells by volume, and a dead tree has up to 40 percent, consisting of beneficial fungi and bacteria, and forming microhabitats for a number of species.