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 leaf disk assay, greenhouse tests and field trials. Among the six polyelectrolytes, 400ppm FO4240SH, FO4490SH and FO4550SH reduced the disease severity of lily leaf blight in leaf-disk tests. Both FO4240SH and FO4490SH also suppressed sporulation of the pathogen on leaf disks. In greenhouse tests, the number and size of lesions on leaves of Lilium oriental hybrid cv. Star Gazer were markedly reduced by FO4490SH and FO4550SH. Field trials showed that the effectiveness of FO4490SH was similar or better than that of procymidone on the reduction of lily leaf blight disease severity. The polymers had no harmful effects on the lily plants. The cationic polyelectrolytes FO4240SH, FO4490SH and FO4550SH reduced the percentage of conidial germination, inhibited germ-tube growth, and also suppressed the esterase production by germ tubes of B. elliptica. All the above evidence indicates that the disease control achieved with polyelectrolytes is due, at least in part, to the reduction of esterase secretion by B. elliptica.