C A S E S T U D I E S
In a study at Ramu Sugar Estate in PNG Kuniata (1998) observed cane yield reduction of up to 32 tons per hectare in 1987. For every 1% cane bored, he estimated the loss per hectare to be 0.82 and 0.13 tons cane and sugar respectively and 0.15% pol percent loss.
- According to research by Kuniata et al. (2001) damage above 20% boring and stalk rot, extraction of sucrose would not be cost-effective.
- 55% extra cost of harvest may be incurred with more than 75% bored canes.
- Highest production losses occur in cases of plants attacked between 5-9 months of age after planting or ratooning.
- A Varietal change in 1987 at Ramu Sugar Estate resulted in an outbreak of Sesamia grisescens due to the susceptibility of the newly opted cultivar. 'Ragnar' which was susceptible to Ramu stunt disease (RSD) was replaced by 'Cadmass' (Tolerant to RSD). But the new variety happened to be highly susceptible to attacks by Sesamia grisescens. The consequence was cane yield reduction by more than 18% (Kuniata & Sweet 1994; Young & Kuniata 1992).
- According to Kuniata (2000) the use of Lamdacyhalothrin and permethrin increased yield by 64% compared to unsprayed plot. However, chemical control requires sustainable use.