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POSTERS: Postharvest pathology and mycotoxins

Effect of 1,4-dimethylnaphthalene on fungal and oomycete storage pathogens of potato tubers
Celeste Dmytryszyn - Michigan State University. Christopher Long- Michigan State University, Raymond Hammerschmidt- Michigan State University

Potato tubers to be used for the fresh market or processing are treated with inhibitors in storage to prevent sprouting and protect tuber quality. One of the currently used sprout inhibitors, the natural product 1,4-dimethylnaphthalene (1,4-DMN), is thought to also enhance skin set and have antimicrobial activity, both of which may help protect tubers from storage diseases. 1,4-DMN was tested for antimicrobial activity against several post-harvest tuber pathogens. These included Fusarium sambucinum, F. oxysporum, F. avenaceum, Helminthosporium solani, Phytophthora infestans and P. eythroseptica. Cultures of each pathogen was exposed for 24 hours to 20 ppm 1,4-DMN (the concentration used in commercial storages) in sealed jars, and growth rates were subsequently measured over time starting at 24 hours. Growth of all pathogens, except P. infestans, was reduced, but none were completely inhibited. Pre- or simultaneous treatment of potato tissue with 1,4-DMN had no effect on infection by F. sambucinum, F. oxysporum, F. avenaceum or P. erythroseptica indicating no direct effects on the pathogen or any resistance inducing effects. Tubers treated with 1,4-DMN in a simulated storage experiment showed no reduction in the amount of silver scurf, caused by H. solani.