Cultivar resistance, infection sources, and effective fungicides identified to control Chrysanthemum cutting rot caused by Plectosporium tabacinum

Cutting rot in Chrysanthemum is caused by the fungus Plectosporium tabacinum and was found on cuttings of ‘Jimba-No.2’ in 2008. The results of inoculation tests indicated that P. tabacinum infects major Chrysanthemum cultivars in Japan and that cuttings can serve as carriers and propagules of the pathogen already in the soil can serve as inoculum. Other P. tabacinum isolates may also infect Chrysanthemum, and P. tabacinum can be present as an endosymbiont in the plant. In tests of various fungicides, captan, 2,4,5,6-tetrachloroisophthalonitrile, and thiophanate-methyl effectively controlled cutting rot in Chrysanthemum.