Leaf-scorch disease of sugarcane in Kenya caused by a new species of Leptosphaeria [bicolor, Fungi]

• Published in: Mycologia Vol. 71; no. 3; pp. 479 - 492
• Main Authors: Kaiser, W.J, Ndimande, B.N, Hawksworth, D.L
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01-05-1979; New York Botanical Garden
• Subjects: Ascospores; Conidia; Fungal diseases; Fungal infections; Fungi; Leaves; Lesions; Plant diseases; Pycnidia; Sugar cane
• DOI: 10.1080/00275514.1979.12021031
• EISSN: 1557-2536
• ISSN: 0027-5514

A new foliar disease of sugarcane (Saccharum officinarum) was observed in Western Province, Kenya. The disease is characterized by spindle-shaped lesions on leaves which eventually enlarge and coalesce to give the foliage a scorched appearance. The Kenya-leaf-scorch disease is caused by a new species of Pleosporales, Leptosphaeria bicolor which has a Stagonospora imperfect state. Ascomata of L. bicolor were observed occasionally in leaf-scorch lesions on naturally infected sugarcane leaves in association with the Stagonospora pycnidia. Both states of the pathogen developed in pure cultures initiated from single ascospores. The perfect state of L. bicolor did not develop on various nutrient media, but formed within 10-15 da on a natural water-agar medium containing autoclaved sugarcane-leaf pieces. Isolates of L. bicolor varied in growth rate, sporulation and colony appearance. Mycelial growth and pycnidial formation were greatest on oatmeal agar. On potato-dextrose agar the optimum temperature for mycelial growth in the dark was 27 C. In controlled inoculation studies, L. bicolor was pathogenic to several sugarcane varieties, but was not pathogenic or only weakly so to napier grass, maize, rice and sorghum.