Abstract:
Branch wilt disease caused by Nattrassia mangiferae (Nattrass) has very wide host range. It attacks trees in forests, orchards, ornamental, and shade trees. It is one of the most hazardous diseases that spread in Wad Medani province, Gezira state, Sudan. In Sudan there is limited information about the disease occurrence. This study is therefore, conducted to study the prevalence of the branch wilt disease in Wad Madani and to study the pathogenicity and host range of the common N. mangiferae isolates in Wad Medani area. The results of the survey revealed that 29 tree species belonging to 15 families were found to be naturally infected. The highest magnitude of the disease was found in ficus (Ficus nitida Thunb.), cassia (Cassia nodosa Roxb.), and baobab (Adansonia digitata L.), where the disease incidence was 100% and the disease severity ranged from 55% to 60%.While the lowest magnitude of the disease was reported in Acacia spp. with 20 % disease incidence and 30% severity. The disease occurrence was confirmed in the different habitats surveyed with the highest disease incidence and severity reported from Attra with 100% and 53%, respectively. Whereas, the lowest incidence (30%-35%) and severity (20%) were recorded from Bankae forest and Hantoub. The laboratory studies revealed that there were 2 different isolates of N. mangiferae. The 1st one was isolated from ficus (Ficus nitida) and the 2nd was isolated from lime (Citrus aurantifolia Swingle.). In host range experiments using seedlings of 12 different tree species artificially inoculated by each isolate, the lime isolate successfully showed symptoms on 11 tree species. Only the seedling of Balanites aegyptiaca remained uninfected. While ficus isolate attacked only two tree species namely F. nitida and Eucalyptus citriodora Hook.
