PROSPECTS FOR EARLY DETECTION OF PYTHIUM BLIGHT EPIDEMICS ON TURFGRASS BY ANTIBODY-AIDED MONITORING

Methods for sampling turfgrass tissue were compared for their effectiveness in monitoring Pythium blight epidemics with enzyme-linked immunosorbent assay (ELISA). Sample areas consisted of marked strips on golf course fairways and tees with bentgrass and annual bluegrass naturally infested by Pythium aphanidermatum. Samples consisted of 1) whole plants picked by hand and assayed as whole plants; 2) whole plants sectioned into lower, middle, and upper strata components; and 3) leaf clippings collected with a reel mower set at a 1.2-cm cutting height. ELISA readings for mowed samples generally matched those for whole-plucked samples (r2 values ranging from 0.457 to 0.601). Fluctuations in detectable Pythium antigens were most pronounced on the uppermost stratum compared with moderate to very little change in ELISA readings for the two lower strata. Several episodes of Pythium antigen increase were detected by ELISA assays of mowed samples, although signs and symptoms of Pythium blight were not evident. However, increases in ELISA readings for Pythium coincided with, but did not generally precede, the onset of blight symptoms with a 2- to 3-day sampling interval. Antibody-aided detection is useful for verification of diagnosis and determination of general Pythium population fluctuations, but current methodology is not satisfactory for advanced detection of blight epidemics.