Drought-related Ips bark beetle outbreaks have been blamed for tree mortality in piñon-juniper woodlands in the Southwest. While efforts to alleviate piñon loss have focused on controlling bark beetle infestation through pesticide use, very little attention has been paid to the potential role of bark-beetle-associated fungi in contributing to tree death by occlusion of conducting tissues. Of particular interest are pathogenic blue-stain fungi in the genus Ophiostoma, which have been shown to kill spruce and other trees. Our aim was to identify and understand tree-associated fungal communities, endophytes and plant pathogens that may play a catalytic role in piñon mortality under drought conditions. Fungi were isolated from core samples of 55 piñons from experimental drought and irrigation plots at the Sevilleta National Wildlife Refuge in central New Mexico. A total of 617 cores were surface sterilized and plated on malt extract agar. More than 100 cultures were isolated and identified using ITS rDNA sequences.
Results/Conclusions
Approximately 22% of the cores were colonized by fungi including close relatives of Nectria, Alternaria, Preussia, Penicillium and Truncatella. Ophiostoma montium, a blue stain fungus, was detected multiple times on dead or dying trees, and the presence of bark beetles was confirmed. This information will aid in the development of new strategies to combat drought-associated decline in piñon populations and understand the mechanisms leading to tree mortality.
