The effect of sublethal heating on sclerotia of Sclerotium rolfsii

Sublethal heating of sclerotia of Sclerotium rolfsii at 50°C for 30 min increased leakage of ¹⁴C-labelled water-soluble organic compounds from the sclerotia, and increased their colonization by bacteria and streptomycetes 574- and 1420-fold, respectively. Disease incidence in bean plants inoculated with heat-treated sclerotia was 43% less than disease incidence produced by unheated ones. Scanning electron microscope observations demonstrated that heating increased the frequency of surface cracks on the sclerotia and the concentrations of bacteria on or around these cracks about 10 times.