4.9.7
EFFECT OF FILM-FORMING POLYMERS ON CONTROL OF LILY LEAF BLIGHT CAUSED BY BOTRYTIS ELLIPTICA

TF HSIEH1 and JW HUANG2

1Department of Plant Pathology, Taiwan Agricultural Research Institute, Wu-feng 413, Taichung, Taiwan; 2Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan

Background and objectives
Epidermis-coating anti-transpirants were able to reduce powdery mildew of sugar beet [1] and had a prophylactic effect, controlling plant diseases such as anthracnose, leaf spot, downy mildew, rust, grey mould, etc. [2]. The effects of anti-transpirants are similar to those of the natural cuticle layer in defence against plant pathogens. Botrytis elliptica, the causal agent of lily leaf blight, enters host plants by direct penetration or indirectly through stomata on adaxial surface or damaged tissue. Therefore, application of film-forming materials onto lily plant surfaces should have a prophylactic effect, reducing lily leaf blight. The purpose of this study is to evaluate the effects of three anti-transpirants and 16 polyelectrolytes on control of the disease.

Results and conclusions
Three anti-transpirants (Folicote, Masbrane, Banole Oil) and 16 polyelectrolytes (bio-gel, gum guar, polyethylene glycol-400 (PEG-400), PEG-4000, polyacrylamide, polyoxyl stearate, polyvinyl alcohol (PVA), sodium alginate, sodium carboxymethylcellulose, poly(acrylamide/DAEM cationic monomer) (24HC, 49HC, 55HC and SC-683), poly(acrylamide/sodium acrylate) (01 OOMA, 0200SHR and 0304MA)] were used to evaluate their effects on control of lily leaf blight caused by B. elliptica using a leaf-disk assay method. Among those, 2000 p.p.m. of PG-400, PG-4000, PVA and sodium alginate, and 400 p.p.m. of 24HC, 49HC and 55HC, significantly reduced disease severity of lily leaf blight. In greenhouse tests, both 49HC and 55HC did markedly reduce the number and size diameter of leaf lesions on Lilium oriental hybrid Star Gazer, but not the others. Infected lily plants, L. oriental hybrid Marco Polo, were treated with 333 p.p.m. of 49HC and 500 p.p.m. of procymidone (sumilex, Sumitomo, Taipei), in the field at Hsin-She, central Taiwan. The results indicated that the effect of 49HC was similar to that of procymidone on reduction of the development rate of disease severity. Spore adhesion of the pathogen was examined using glass coated with non-ionic (0200SHR), anionic (0100MA and 0304MA) or cationic (24HC, 49HC and 5SHC) polyelectrolytes. It was found that a higher percentage of spores attached to the glass surface with cationic polyelectrolytes. Cationic polyelectrolytes were also more effective in reducing the percentage of spore germination, length of germ tubes and growth of mycelia. In addition, the efficiency of cationic polyelectrolytes on coagulating enzymes released by the pathogen was also investigated.

References
1. Gale J, Poijakoff-Mayber A, 1962. Phytopathology 52, 715-717.
2. Hsieh TF, Huang JW, 1997. Plant Pathology Bulletin 6, 89-94.