Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2000
Publication Date: 1/1/2003
Citation: LESICA, P., ATTHOWE, H.E., DUGAN, F.M. INCIDENCE OF PERENNIPORIA FRAXINOPHILA AND ITS EFFECTS ON GREEN ASH WOODLANDS IN EASTERN MONTANA. CANADIAN JOURNAL OF BOTANY. 2003. v. 182 p. 153-159. Interpretive Summary: Green ash is the dominant woodland tree in many areas of the northern Great Plains. It is subject to a number of plant health problems, including the wood-rotting fungus Perenniporia fraxinophila and a dieback of unknown etiology. The incidence of the fungus in these green ash stands has never been previously quantified, nor its potential relation to dieback investigated. This research shows that the incidence of P. fraxinophila can be as high as 67 percent, and that the fungus has potential to make openings in the canopy by rendering branches or boles subject to breakage. Nearly a third of the instances of dieback were not accompanied by either detectable rot nor the presence of sporocarps. So, although the fungus alters canopy structure by rotting boles and branches, the likelihood that the fungus is a direct cause of dieback is considerably diminished.
Technical Abstract: Incidence of Perenniporia fraxinophila sporocarps on green ash trees at six sites in east-central Montana ranged from 0-67 percent and averaged 38 percent. Sporocarps of other wood-rotting basidiomycetes were not observed on sample trees. Rot was detected in basal cores from an average of 23 percent of trees. Seventy-four percent of trees with rotten cores also had sporocarps. Mean canopy dieback (MCD) at the sites ranged from 22-50 percent. MCD was 54 percent for trees with sporocarps and 37 percent for those without sporocarps, but 27 percent of trees lacking both sporocarps and rotten cores had MCD greater than 50 percent. No evidence was found that P. fraxinophila is a cause of canopy dieback. Although not a cause of canopy dieback, P. fraxinophila is a factor in opening of canopies because internal rot leads to breakage of limbs and boles during meteorological events. Trees originating via multiple sprouts from stumps were not significantly more infected than trees with single boles.