Searching alternatives for biological control of Rhizopus stolonifer in tomato postharvest.
German Garcia, P. and Marina Cotes, A.
Fitopatologia Colombiana. Volume 25, Number 1, 2001. Pages 39-47.
2001
บทคัดย่อ
The main objective of this work was to evaluate the biological control activity of native yeast against soft rot of tomato caused by Rhizopus stolonifer. Nine yeast isolates capable of growing at 6 and 25 deg C were selected. Tomatoes were damaged with a cork borer to cause gaps of 6 mm wide and 3 mm deep. Tomatoes were inoculated with successive pathogen dilutions ranging from 102 to 106 sporangiophores/ml. In all cases a localized infection was obtained. The concentration of 104 sporangiospores/ml was selected for more tests, since this concentration produced a disease incidence of 100% and >80% severity. A test was carried out under controlled temperature conditions (6-8 deg C and 17-22 deg C) at a humidity of 90%. A yeast suspension, adjusted to 107 cells/ml, was applied into the damaged tomatoes, after which they were incubated at 6-8 deg C and 17-22 deg C during 24 h. The previously selected concentration of R. stolonifer was inoculated and the incubation continued. The assessment of infection diameter was carried out every 2nd day and finalized at the moment in which the fungus colonized the fruits. In the control treatment (inoculated only with the pathogen), this point was reached after 18 days at 17-22 deg C and 28 days at 6-8 deg C. The 9 antagonistic microorganisms offered some protection against R. stolonifer resulting in slower development of disease symptoms. Only three yeasts, Lv050 (Pichia anomala), Lv031 (P. onychis) and Lv027 (P. onychis), resulted in >85% protection at both storage temperatures.