Sugarcane Losses Due to Shoot and Stem Borer Damage and Defoliation

Abstract

Using the single tiller method and the sugarcane variety F 140, an assessment was made of the potential yield losses due to shoot borer damage. Losses were closely related to the level of shoot borer infestation and ranged froma 11% yield drop with 3-8% of cane shoots damaged, to a yield drop in excess of 52% when more than, 46% of shoots were damaged. The relationship between yield loss and berer damage was able to be described by the regression y = 2.36 + 1.93 X - 0.02X2 where x represents the level of shoot damage by borers and y the percentage yield loss. When the level of shoot borer infestation was controlled by the strategic us eof insecticides, yield losses which resulted were 25, 27 and 40% pespictively for 11, 15 and 24% of cane shoots damaged.
Using the analytical method for estimating stem borer infestation and damage in field plantings in five locations, stem borer damage was found to have had no effect on yield but did reduce the CCS by an average of 7%
In simulated damage by leaf eating insects through hand defoliation teatments at 41/2 months after planting using the variety F 140, it was demonstrated that sugarcane can toterate up to a 50% reduction in leaf area without any effect on yield. However, yield decreased by 14 and 24%, rspectively, in the 75 and 100% defoliation treatment.