Alternaria leaf blight disease management in sunflower (helianthus annuus, l.) with sawdust or ash extract
The effectiveness of sawdust or ash extracts of Gmelina arborea and Ficus exasperate to manage Alternaria leaf blight of two sunflower varieties (SAMSUN 3 and SAMSUN4) was investigated at the Teaching and Research Farm, Federal University of Agriculture, Abeokuta (7o15’N; 3o25’E) Ogun State, Nigeria during 2014 early cropping season. The treatments consisted four sawdust or ash extracts, a synthetic fungicide Benlate (Benzimidazoles 50% WP) and an unsprayed control in a randomized complete block design with three replicates. Sunflower plants were sprayed with 100%(w/v) extracts once every two weeks using pneumatic hand sprayer, from the third week after planting. Data were collected on incidence, severity of Alternaria leaf blight disease and yield indices under sprayed and unsprayed plots and subjected to analysis of variance using the statistical analysis software “CoStat 6.4”. Results showed that all extracts significantly (p≤ 0.05) reduced the incidence and severity of the disease. Especially, ash extract of F. exasperate distinctively reduced the number of infected leaves and lesions on foliage and resisted disease development translated to protected achenes and flowers from infection. Seeds from the plots sprayed with sawdust or ash extracts of both tropical trees induced significantly (p≤ 0.05) lower fungal infection (27.04%) compared to unsprayed plots (58.27%). Similarly, germination of seeds from the sprayed plants was higher (92.71%) than that of control (23.14%). In general, sawdust or ash extracts of G. arborea and F. exasperate were comparable in their effect to control Alternaria leaf blight disease of sunflower varieties.