Viability of Moniliophthora roreri on cocoa beans under micro-fermentation and long-term survival on carrier materials

• Published in: Plant disease
• Main Authors: Estrela Junior, Ailton da Silva, Solís, Karina, Sobrinho, Catharina Coltrim de Mattos, Catota, Arturo Ivan Garzon, Peñaherrera, Sofia, Vera, Danilo Isaac, Solis Bonilla, Jose Luis, Moraes, Willian Bucker, Laranjeira, Delson, Gramacho, Karina Peres
• Format: Journal Article
• Language: English
• Published: United States 08.05.2023
• Subjects: Dissemination; Germination; Frosty pod rot of cacao; Biosafety; Epidemiology; pathogen survival; Subject Areas
• ISSN: 0191-2917; 1943-7692

The viability of inoculum was evaluated during the micro-fermentation process of diseased and healthy pulp-seed masses and on a range of carrier materials: aluminum, cloth, glass, paper, plastic, raffia, and rubber tire. Fungal survival was assessed before the micro-fermentation (0 hours) and every 24 to 96 hours by the growth of colonies in potato-dextrose-agar and sporulation in seed shells. Colonies of and sporulation on seed shells were observed from seeds not submitted to micro-fermentation. No growth was recovered from diseased cocoa beans after 48 hours under the micro-fermentation. The viability of M. roreri spores recovered from carrier materials was evaluated at 7, 15, 30, 45, and 100 days after inoculation (DAI) by collecting spores, plating them on Sabouraud dextrose yeast extract agar amended with chloramphenicol (50 mg L ). The viability was determined by counting germinated and ungerminated spores under a light microscope (40×) after incubating in a moist chamber at 26 ±2 °C for 72 hours. Spores maintained long-term viability on all tested carrier materials toward the end of the experiment (overall 26%), with significant differences ( < 0.05) among them. Maximum spore viability occurred at 7 and 15 DAI, with cloth and plastic carrier materials considered at high risk of acting as vehicles for the fungal spread. Mathematical models of spore viability over time were fit to the data using the Bayesian information criterion. Findings confirmed the importance of the fermentation process to hamper growth and the potential of carrier materials for fungal dispersal.