Abstract
An acoustical particle counter and rotorod samplers were used to monitor spores of Uromyces phaseoli var. typica on snap bean [Phaseolus vulgaris ''Bountiful''] during the course of 4 epidemics in controlled environment chambers. In the acoustical counter, airborne particles are drawn through a capillary section of a tubular acoustical element, where particles > 5 .mu.m in diameter shed vortices as they are accelerated less rapidly than the surrounding air. Pressure changes caused by these disturbances in the laminar flow cause sound waves detectable with an electret microphone. Acoustical counts and rotorod counts were highly correlated (r = 0.98), with approximately 1 acoustical count for every 26 rotorod counts. Disease increase as measured by a visual rating scale was highly correlated with both acoustical counts (r = 0.94) and rotorod counts (r = 0.96). Immediate digital readout, simplicity of design, and large sampling volume give the acoustical counter advantages over other particle counting methods for some phytopathological investigations.

This publication has 0 references indexed in Scilit: