Effect of film-forming polymers on control of lily leaf blight caused by Botrytis elliptica

The effectiveness of film-forming polyelectrolytes for the control of lily leaf blight caused by Botrytis elliptica was evaluated using laboratory a l eaf disk assay, greenhouse tests and field trials. Among the six polyelectr olytes, 400 ppm FO4240SH, FO4490SH and FO4550SH reduced the disease severit y of lily leaf blight in leaf-disk tests. Both FO4240SH and FO4490SH also s uppressed sporulation of the pathogen on leaf disks. In greenhouse tests, t he number and size of lesions on leaves of Lilium oriental hybrid cv. Star Gazer were markedly reduced by FO4490SH and FO4550SH. Field trials showed t hat the effectiveness of FO4490SH was similar or better than that of procym idone on the reduction of lily leaf blight disease severity. The polymers h ad no harmful effects on the lily plants. The cationic polyelectrolytes FO4 240SH, FO4490SH and FO4550SH reduced the percentage of conidial germination , inhibited germ-tube growth, and also suppressed the esterase production b y germ tubes of B. elliptica. All the above evidence indicates that the dis ease control achieved with polyelectrolytes is due, at least in part, to th e reduction of esterase secretion by B. elliptica.