Further Eyaluation Oif Fungicides for Control of Pineapple Disease of Sugarcane

In a series of screening trials a number of new, non-mercurial fungicides have shown promising results in controlling pineapple disease of sugarcane (Ceratocystis paradoxa). Several of the fungicides tested are as effective as Aretan and Benlate and are now registered for use in sugarcane. Growers now have a choice of effective non-mercurial fungicides for sett dip treatment. Poor germination of sugarcane setts under conditions that are not optimum for rapid germination can often be attributed to pineapple disease, caused by the fungus Ceratocystis paradoxa. Whenever conditions for germination are adverse, because of low soil temperatures, drought or waterlogged soils, infection of the setts can affect germination considerably. Varieties differ in their susceptibility to pineapple disease but gerinination failures can occur in most varieties under adverse conditions if control measures are not applied before planting. An effective way of controlling the disease is by dipping the setts in a protective fungicide before planting. Because of the high costs of gap filling and the deleterious effects of poor and slow germination 011 cane growth, sett treatment is always advisable. Treatment is pa.rticularly recommended for autumn planting, when conditiins are often adverse, and after hot water treatment, when susceptibility may be increased. The withdrawal of registration of compounds based on mercury for use in sugarcane in South Africa, and the phasing out of these materials in recent years, have necessitated a search for alternative, effective fungicides. Benlate (benomyl) was the first non-mercurial fungicide found to provide effective control of pineapple disease, (Mitchell-Innes and Thomson3 and it has now been used by growers for several years. A number of other fungicides have also been reported to show promise (Mitchell-Innes and Thomson3). This paper describes three recent field trials for the evaluation of fungicides for control of pineapple disease.