The long-lived giant sequoias are often thought to be impervious to insect and pathogen effects. As giant sequoia ecosystems are more closely monitored, however, pest effects may become more noticeable. The tree had decay in several large support roots and was growing on the edge of an annosus root disease center. Thirteen saplings died in two years in an area of about 1 acre. Conks of the annosus fungus were found in white fir and incense-cedar stumps in the plantation, and mycelial fans of Armillaria sp. were present at the root collar of each dead tree.
Tests are in progress to determine what species of Armillaria are present.
No evidence has yet been discovered to explain what triggered the mortality. Jeffrey pine . Increasing Jeffrey pine mortality became evident in 1990 around the east and south sides of Lake Tahoe. Death of Jeffrey pines is often the result of interactions between moisture stress, the Jeffrey pine beetle, overstocking, and annosus root disease in some locations. The mortality is of particular concern because it is in high-use, developed sites and dispersed recreation areas, as well as on private properties.