Pathogenicity of fungi collected in northern Ghana to Striga hermonthica.

Thirteen fungal species were isolated from diseased plants of Striga hermonthica (Del.) Benth in northern Ghana. The pathogenicity of 12 isolates of the fungal species including Curvularia fallax Boed, Fusarium equiseti (Corda) Sacc., Fusarium equiseti var. bullatum (Sherb.) Wollenw., F. oxysporum Schlecht, F. solani (Mart) Sacc., Macrophomina phaseolina (Tassi) Goidan, and Sclerotium rolfsii (Sacc.) were evaluated against S. hermonthica under controlled environmental conditions. All isolates were pathogenic to S. hermonthica when propagated on wheat (Triticum aestivum. L.) grains and incorporated pre-plan ting into the soil. However, their virulence differed. Two isolates of F. oxysporum and one isolate of F. solani reduced the emergence of S. hermonthica by 88%. 98%, and 76%, respectively. Sorghum (Sorghum bicolor (L.) Moench) yield was increased by 26% when S. hermonthica was controlled. In contrast, in the control treatment with S. hermonthica no yield could be obtained. The P. oxysporum isolates were not pathogenic on sorghum. Germination tests indicated that the F. oxysporum isolates were highly pathogenic to S. hermonthica seeds. Although the F. solani isolate reduced the emergence of S. hermonthica in the pot experiments, it did not influence germination. This indicates that pathogens may attack different stages in the life cycle of S. hermonthica. [ABSTRACT FROM AUTHOR]