Economics of fungicide application schedules for the control of wattle rust (Uromycladium acaciae) in Acacia mearnsii plantations, South Africa

Payn R.G, Nxumalo, T. and Little K.M.
Publication Type
Technical Note
Publication Year
TN 04-2018

Acacia mearnsii (black wattle) plantations in South Africa cover approximately 110 000 ha. Uromycladium acacia (wattle rust) has spread over Limpopo to the Western Cape of South Africa. This disease of black wattle causes reductions in growth and mortalities in severe infections. In October 2014 six trials were initiated in Mpumalanga and KwaZulu-Natal to determine the effectiveness of fungicides, varied application schedules, and adjuvants for the management of wattle rust. Relative growth for Biomass Index was compared to untreated controls to obtain comparisons within and between sites. Costs versus benefit were compared using a two-way table to determine the most optimum treatment. The largest portion of treatment costs was attributed to the cost of fungicide. No treatment was found to be optimal for the recommended rate of application. The use of adjuvants increased the cost of treatment, without additional benefits in terms of growth. Control of wattle rust is beneficial, although costly if overapplied. Rotation-end data is required to determine whether fungicide use is economical for managing wattle rust over an extended period of time.