The sugar-cane borer (SCB), Diatraea saccharalis (F.), and the ratoon stunting disease (RSD) bacterium independently caused significant reductions in stalk weight, cane tonnage and sugar yield. A three-fold difference was found in the comparison of per cent loss of cane tonnage due to RSD alone with that due to the disease in combination with SCB damage in first ratoon sugar-cane. Variance analysis failed to detect interaction between damage by SCB and that by RSD. The data analysed were obtained from an experiment of six replication which evaluated the effects of SCB damage and RSD on sugar-cane yield in Louisiana. We used the randomized complete-block experimental design with split-plot arrangement of treatments. Three schedules of insecticide application to the growing cane, against SCB were the main plots whilst the subplots comprised of RSD inoculation vs. no inoculation of sugar-cane plants grown from seed canes with light vs. severe SCB damage.
