Original Articles

The economic benefits of fungicide treatment of maize for the control of grey leaf spot (Cercospora zeae-maydis) in KwaZulu-Natal

Published in: South African Journal of Plant and Soil
Volume 14, issue 1, 1997 , pages: 43–48
DOI: 10.1080/02571862.1997.10635079
Author(s): J., M.J. Ward, Republic of South Africa, M., A.G. DarrochDepartment of Agricultural Economics, Republic of South Africa, M.D. LaingDepartment of Microbiology and Plant Pathology, Republic of South Africa, A., L.P. CairnsDepartment of Agronomy, Republic of South Africa, H.M. DicksDepartment of Statistics and Biometry, South Africa

Abstract

Grey leaf spot (Cercospora zeae-maydis Tehon and E.Y. Daniels) is a relatively new disease of maize in South Africa and is capable of reducing grain yields by 20–60% in KwaZulu-Natal. Fungicides are widely used for control, but must be applied at the correct stage of disease development. Repeated applications may be necessary for effective control to be achieved. There is a paucity of information on the economic justification of these control measures. The aim of this study was to estimate the economic benefits of single and multiple sprays applied to maize at different stages of disease development. The economic analysis was based on the average operating costs of 18 dryland maize farms in the Winterton and Karkloof areas, where fungicides have been used to control the disease. These costs were used in the analysis of data generated from trials at Cedara to determine the most effective times and frequency of fungicide application for the control of grey leaf spot. Triple-spray treatments under both high and low disease levels provided better control of disease (higher-yield gains over non- sprayed treatment) but did not always give highest added profit ha−1. Least risk-averse farmers would probably select the triple-spray programme under high levels of disease, since it provided highest added profit ha−1. The double-spray programme, with lower added profit ha−1 under high levels of disease may, however, be preferred by more risk-averse individuals. Under low levels of disease, the single-spray treatment, giving higher added profit ha−1, may be more attractive to least risk-averse farmers.

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