Banana Disease: Malayan leaf Spot
This is usually a minor disease in Fiji, Tonga, Western Samoa and the highlands of peninsular Malaysia and Papua New Guinea. Severe development occurs in areas of Fiji with > 1 m of annual rainfall where temperatures are below 24 degree C, and on some local cultivars in Papua New Guinea.
Symptoms are varies in the different locations. In Fiji, lesions on the upper leaf surface are diamond shape, light grey, 2 - 4 x 3 – 5.5 mm, and have 0.5 mm wide black borders. Profuse growth of the causal fungus, Haplobasidion muscle, occurs on the leaf undersurface.
In Malaysia, lesions have dark purple borders, are pale grey on the upper and pale brown on the lower surface, and are either ellipsoid (2 – 4 x 3 – 12 mm) or round (2 – 5 mm in diameter). Lesions are similar in Papua New Guinea, and large patches of confluent necrosis can develop. Symptoms develop as early as the second or third leaf on local ‘Mala’.
Single to six conidiophores of H.musae are produced at the ends of hyphae that arise through the epidermis on the leaf’s lower surface. They are straight or flexuous, pale brown, one to four celled and 50 – 110 x 4 – um. They terminate in a subglobose cell. Conidia are spherical, brown, verrucose, 4 – 6 um in diameter, and borne singly or in chains of two to five.
Although control measures usually are not needed, maneb was effective. Spray oil enhanced disease development.
Banana Disease: Malayan leaf Spot
