Forest pathogens and disease assessment of six coniferous species in Jigme Dorji National Park (JDNP), Bhutan
Forest diseases are important limiting factors for structure and composition of healthy ecosystems, productive and protective equation. This study investigated 3,442 coniferous trees in JDNP belonging to 6 species and confirmed a total of 20 forest pathogens, 15 fungi belonging to 11 families, 3 mistletoes belonging to 2 families and 2 insect pests belonging to 2 families. Shinnon Wiener Index (0.0001-2.4999) concluded that hosts have low to medium pathogens diversity with average of host to pathogens ratio 1:4. However, each host’s pathogens are evenly distributed according to Pielou evenness index (0.7500-1.0000). Mean disease incidence percentage was 28.8 (SD=13.21) and disease severity index was 0.415 (SD=0.165). Study shows that disease incidence and severity index have significant relationship (r=0.9, p=0.05) and confirmed 65% of diseases in pure forest and 35% in mixed forest (χ2=0.14, p=0.05, df=1). Study also concluded that 19.16% of pathogens were sharing same host.
KEYWORDS: Forest diseases, pathogens, fungi, insect pests, mistletoes.