Ingress, internal spread and some factors affecting pathogenicity of Diplodia tubericola (E. and E.)Taub. in sweet potato
1984
Sardsud, V. | Divinagracia, G.G. (University of the Philippines at Los Banos, College, Laguna)
Mycelial discs induced disease development faster than spores suspension. The mycelia could not penetrate through the well-formed periderm of sweet potato storage roots inoculated 12 days after harvest. On newly harvested storage roots with loosely formed periderm, the mycelia invaded intercellularly and were restricted in the cork layer. A periderm was formed in response to penetration which separated the healthy tissues from the penetrated cells. Inter and intracellular penetration through wounds made on the storage roots were observed 6 hours after inoculatiion and pyenidial formation was noted at the cork cambium layer 4 days after. Incubation for 48 hours in moist chamber and exposure under room condition was recommended for disease initiation. Disease development was favored at 30 C. Six day-old storage roots were more susceptible than the newly harvested or 3-day old roots when inoculated with the fungus. Injured surfaces of newly harvested roots inoculated with the fungus was observed to form a wound periderm which protected the healthy tissues from mycelial penetration
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