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Ascochyta chrysanthemi Toxin: Production and Properties. D. L. Schadler, National Science Foundation Graduate Trainee, Department of Plant Pathology, Cornell University, Ithaca, New York 14850; D. F. Bateman, Professor and Chairman, Department of Plant Pathology, Cornell University, Ithaca, New York 14850. Phytopathology 64:779-784. Accepted for publication 17 December 1973. DOI: 10.1094/Phyto-64-779.

Filtrates from 14-day-old cultures of Ascochyta chrysanthemi contained a toxin capable of inducing a complex of foliar symptoms in chrysanthemum similar to those that occur on plants that are stem-inoculated with the pathogen. A. chrysanthemi toxin sufficient to produce typical foliar symptoms on chrysanthemum accumulated within 6 days in liquid culture; dilution endpoints of filtrates of 14-day-old cultures for symptom induction on chrysanthemum were between 1:100 and 1:1,000. The toxin, in culture filtrates or partially purified preparations, was stable in storage at 4 C for 3 yr. A. chrysanthemi toxin was destroyed by boiling and by charring, but not by autoclaving at 121 C unless autoclaved in strong acid or strong base; it was not extracted from culture filtrates by organic solvents but was absorbed by activated charcoal and was retained by DEAE cellulose at pH 8.0. This toxin was not precipitated in 66% methanol; it was dialyzable but was retarded in Sephadex gels with exclusion limits above 1,000 molecular weight.

Additional keywords: chrysanthemum ray blight, Mycosphaerella ligulicola.