Minimising damage from a pest in the South African sugar industry.

John Hearne

RMIT University, Melbourne, Australia

Petrovious Horton and Des Conlong

SA Sugar Experimental Station, Mt Edcombe, South Africa.

Abstract

The stalk borer Eldana saccharina is a cause of major loss to the South African sugar industry. A consequence of Eldana infestation is that farmers face a dilemma just before the sugar mills close for about 3 months each year. If they harvest their crop early, before the mills close, the sucrose content and hence the revenue will be lower. On the other hand, waiting for the mill to re-open and the sucrose content to increase has its risks. During this period an Eldana problem can worsen, and cause such damage that the whole crop has to be abandoned. This outcome is highly dependent on temperature conditions.

To assist farmers in their decision a model has been developed that includes cane growth and the population dynamics of Eldana. The Eldana model includes the effect of temperature on the physiological development of individuals in each life-stage of the insect. For various temperature scenarios the model can determine the crop damage that will result and hence the loss of revenue from the crop. Historical temperature data can then be used to determine the risk involved in delaying harvest until the mills re-open.