Culture of the Sweet Potato Scab Fungus (Sphaceloma batatas Saw.)

Fredeswinda O. Lao and G.G Divinagracia


Various methods were tried to isolate the causal fungus of sweet potato stem and foliage scab. The following isolation techniques were successful: (a) small pieces of diseased tissues from stems and leaves were planted in petri dishes containing either Leonian ‘s, onion or potato dextrose agars and incubated at various temperatures; and, (b) free hand sections of plant tissues through the lesion were transferred on malt, carrot, sweet potato leaf decoction and potato dextrose agar drops on glass slides and kept in a humid atmosphere in petri dishes. The fungus grew well on sweet potato decoction agar, carrot agar, malt agar, yeast extract agar, and oatmeal agar. Its growth was better at 25 and 30 C than at 15 and 20 C on both malt and carrot agars; no growth occurred at 10, 35 and 40 C. Its growth was optimum at pH 6.0 to 8.5 and grew better when exposed to alternate light and dark and continuous light than under natural light and continuous dark. The fungus was induced to produce conidia.

Annals of Tropical Research 1(1):(1979)
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