Recovery Plan for the Northern Spotted Owl - DRAFT

D. DiseasesForest diseases in the Pacific Northwest are caused mainly by fungi and dwarfmistletoes. Bacteria, viruses, and nematodes also cause diseases but to a minorextent. The major diseases can be classified as foliage diseases, heart rotsor bole decays; stem and branch diseases (cankers, rusts, dwarf mistletoes),root rots; and cone and seed diseases. More recently "decline diseases" havebeen recognized whereby trees tend to decline and slowly die over a period ofyears. Decline usually occurs in areas where chronic levels of air pollution ordrought have induced stress allowing insects and diseases to gain a foothold.Although the general types of diseases are similar in the West Cascades, Kmamath,and East Cascades subregions, the species of fungi and dwarf mistletoestend to change with the tree species. Some disease organisms have broad hostranges while others have relatively narrow host ranges (Table F.5). There arehundreds of disease organisms in these forests but only the most important/Table F.5. Important forest diseases in the West Cascades, Klamath, and EastCascades subregions.Common Name Causal Agent Tree SpeclesFOLIAGE DISEASESWest Cascades SubregionSwiss needle cast Phaeocryptopus gaumanhi Douglas-firRhabdocline needle cast Rhabdocline pseudotsugae Douglas-firBrown felt blight Herpotrichia nigra True firsCedar leaf blight Didymascella thujina Western redcedarBynum's blight Lophodermella morbida Ponderosa pineROOT ROTSPhellinus root rot Phellinus weiril Douglas-fir, mountainhemlock mostsusceptibleArmillaria root disease Armillaria ostoyae All conifers (Douglas-firmost susceptible)Annosus root and Heterobasidion annosum Western hemlock andbutt rottrue firs mostsusceptibleBlack stain root Leptographium wageneri Douglas-fir mostdiseasesusceptibleRhizina root rot Rhizina undulata Douglas-fir41-38continues-