Interaction of spore concentration and fungicide concentration on the control of pineapple disease of sugar cane setts

Abstract

Sugar cane setts were artificially inoculated with spores of Ceratoytis paradoxa (pineapple disease), treated with a range of concentrations of mercuric fungicides and planted out in the field, near Brisbane, Queensland. At a constant concentration of inoculum, infection (as judged by shoot emergence, eye sprouting, and macroscopic signs of infection) decreased as the concentration of the fungicide increased. When the concentration of spores in the inoculum was increased the fungicide concentration needed to be increased to maintain a given level of control. Of the two fungicides tested, BSM11 (10 per cent phenyl mercuric acetate and 50 per cent potassium 2,4,6 trichlorophenate) was slightly more effective than Aretan (6 per cent w/w organically combined mercury). The possibility of phytotoxicity of the mercury fungicide was shown. The complicating effect of infection by other organisms is discussed.