Abstract: Background and Objective: Black pod disease of cocoa affects every part of the pant development from nursery to the pod. Raising healthy cocoa seedlings at the nursery, therefore, ensures better seedling establishment in the field. This study sought to develop a biocontrol option for seed decay and damping-off disease of cocoa and at the same time, promote seedlings growth with antagonistic microbes. Materials and Methods: The experiment consisted of two parts; preliminary tube experiment and pot experiment. Oven sterilized topsoil in plastic tubes were infested with P. palmivora suspension prepared from a 14 days-old culture and incubated on a planthouse bench. After two weeks, infested soils were separately drenched with broth supensions of the microbial antagonist sowing. Four replicate tubes per treatment were established. In the pot experiment, similar treatment was subjected to a steam topsoil for two weeks. The infested soil distributed in separate tubes or plastic pots and either drenched with NB suspension of the rhizobacterium, PDA suspensions of Aspergillus and Penicillium spp. or seeds dipped in microbial suspensions before sowing. The setups were maintained in the planthouse for six weeks and disease assessments as well as growth parameters were made or recorded on resulting seedlings respectively. Results: Broth suspensions of the microbial antagonists either used as a soil drench on Phytophthora-infested soil or as seed dip, prevented seed decay, damping-off and promoted seedlings growth with significantly higher (p PubDate: 20 October, 2021
Abstract: Background and Objective: Potato sclerotium rot disease causes a very high impact on the quality and quantity of potato production in Chiang Mai, Thailand. It has become a recurrent problem of potato production. The soil-borne pathogens of crop incited by Sclerotium rolfsii are very difficult to be managed because it produces sclerotia for the long-term survival in the soil. The objectives of this study were to identify pathogens and evaluate fungicides and wood vinegar for their efficacy against pathogens. Materials and Methods: The pathogens were identified based on morphology. The pathogenicity of fungal isolates was tested in the laboratory and compared with the non-treated control. Six fungicides and wood vinegar were tested by the poisoned medium technique, the analysis was arranged in a completely randomized design with 5 replicates of each treatment. Results: The fifteen fungal isolates were identified as S. rolfsii based on mycelial and sclerotial characters. A pathogenicity test was conducted in the laboratory, where the symptoms of rotten tissues and penetration of pathogens were observed. In vitro evaluation of fungicides and wood vinegar, found that the mycelial growth and sclerotial germination were completely inhibited by etridiazole+quintozene and mancozeb at recommended concentration and wood vinegar at 1% concentrations. Conclusion: The results revealed that S. rolfsii caused potato sclerotium rot disease in Northern, Thailand. The highly effective fungicide against S. rolfsii was etridiazole+quintozene and mancozeb. For the efficacy of wood vinegar, it can be decreased in vitro at 1% concentration onward. PubDate: 20 October, 2021
Open Access journal
