Effects of elevated atmospheric carbon dioxide on the biological controlof coffee leaf rust under controlled conditions

Abstract: The effect of elevated atmospheric CO2 concentration on biological control of coffeeleaf rust, caused by Hemileia vastatrix, was evaluated by leaf disc assay, under controlledconditions. The biocontrol agents Bacillus subtilis, Bacillus pumilus and Lecanicilliumlongisporum were applied 24h before, 24h after, and simultaneously with the H. vastatrix on leafdiscs (diameter of 1.5cm). The CO2 concentrations tested were: 380, 430, 700 and 1300ppm forB. subtilis and B. pumilus; and 380, 430, 670 and 1200ppm for L. longisporum. The antagonistswere not affected by CO2 concentrations. B. subtilis was the most effective in controlling thedisease when applied before and simultaneously with pathogen.