Morphological Characterization of Hypoxylon Wood Rot Fungus in Kenyan Tea.

Abstract

Hypoxylon fungi species causes Hypoxylon wood rot disease in tea (Camellia sinensis (L) O. Kuntze). It exists in both asexual and sexual states. To assess the diversity of the fungi in Kenya, 58 fungus isolates were collected from different tea growing regions in Kenya and characterized based on cultural and morphological features. Radial growth of the different isolates on PDA differed significantly. Based on visual assessment of cultural similarity, 10 groupings were observed. The characteristics were mainly effused pulvinate stromata, composed of mainly spherical perithesia and amyloid asci with brown ellipsoid in-equilateral ascospores. Hypoxylon fungi were prevalent (disease index 0.76 to 0.82) in clonal as compared to seedling teas (0.05-0.36). The disease was fairly prevalent at elevated tea growing areas (2100-2250 m asl) than at 1826-1969 m asl. Morphological characteristics of the stromata did not show much variation with respect to tea growing areas; however, treatment of stomatal bodies with 10% KOH released extractable pigments (brown), indicating that H. species is infecting tea in Kenya.