Colletotrichum alatae is a specific pathogen of Dioscorea alata responsible for the foliar anthracnosis in this Yam specie. The only product registered in Puerto Rico for the control of the anthracnose is based on the active ingredient Azosystrobin, which have shown to developed resistance on Colletotricum spp. Chitosan is a de-acetylated product of Chitin which have shown plant protection capabilities, particularly as a fungicide. To evaluate the efficacy of Chitosan on Colletotrichum alatae

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... vitro, the radial growth and a microtiter assay was performed. Three chitosan products and three concentrations were evaluated, a positive (Azosystrobin) and a negative control were also included. The results of the radial growth show that the best treatment in the control of the mycelial development is the Azosystrobin followed by the low molecular weight at 1000 ppm. In the other hand, the microtiter assay shows that the best treatment is the low molecular weight at 1000ppm. These results suggest that chitosan could be a potential product to control anthracnose which works better in the conidial stage of the fungi. of chitosan at the field level, because chitosan can reduce the severity of the disease and induce defense response in the plant.