Infectivity of the Fusarium fujikuroi Species Complex (FFSC) on Maize (Zea mays Lam.) in Gauteng, South Africa

Background and Objective: Of the world’s top ten phytopathogenic fungi, Fusarium is the only group represented by more than one genus causing yield losses on crops and also producing a wide range of mycotoxins in food and feed products which can cause deleterious effects on human and livestock. The study aimed to investigate the pathogenicity of some Fusarium species isolated from Gauteng, South Africa on maize. Materials and Methods: A complete randomized block design with 26 isolates, belonging to the members of the Fusarium fujikuroi species complex (FFSC) was screened in 2017 for their infectivity on maize in Plant Protection Research Institute (PPRI), Pretoria, South Africa. The parameters tested included germination efficiency, plant height, dry weight, and disease severity. The results were analyzed using Duncan’s Multiple-Range Test at a 5% level of significance. Results: The infection with F. burgessii and F. nygamai isolates PPRI 21048 and PPRI 21265 produced the highest and lowest disease severity index of 72.89% and 41.33%, respectively. These caused a reduction in plant height by 76.07% and 44.22%, as well as a reduction in dry weight by 58.24% and 20.50%. There was a significant difference (p<0.05) amongst the species and isolates of the same species. A low, yet significant negative correlation was observed both between disease severity and plant height (r = -0.6463, p = 0.0004) on the one hand and between disease severity and dry weight (r = -0.5038, p = 0.0087) on the other hand. Conclusion: The Fusarium species have caused varying degrees of infectivity on maize from a reduction in plant height to a reduction in dry weight with significant differences among the Fusarium species and isolates of the same species.