Relationships of rat damage to physical and yield characteristics of Hawaiian sugar cane

Two long-term data sets containing information on rat damage levels and measurements on physical and yield characteristics on a number of varieties of sugar cane were examined to ascertain if a relationship could be detected between rat damage and the other variables. One data set was collected over 6 years from experimental field plots on 5 plantations. The other data set was collected operationally over 9 years from a single plantation. Most correlations were not large and varied in sign among varieties, but some patterns of relationships with rat damage levels were indicated. The experimental field plot data provided indications that rat damage may be negatively related to elevation and the amount of sucrose in the sugar cane juices (percent pol) and positively related to the density of sugar cane stalks. The data from the single plantation indicated correlations of rat damage with the percentage of sour stalks in the field and with elevation. Our general conclusions are that overall sugarcane yields and quality are probably more influenced by cultural practices and environmental conditions than rat damage as a determining factor.