Antagonistic activity of Trichoderma isolates on pathogenic fungi, colletotrichum musae, colletotrichum acutatum and Botryodiplodia theobromae
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Date
2014-07-04
Authors
Janaththani, P.
Adikaram, N. K. B.
Sooriyapathirana, S. D. S. S.
Dhanapala, M. P. C. S.
Journal Title
Journal ISSN
Volume Title
Publisher
The university of Peradeniya
Abstract
Plant disease management is an uphill task. Biological control is hailed as a safe approach to manage plant diseases. Trichoderma is a soil inhabitant and it is well known as a potential biological agent to control fungal pathogens of plants. Several commercial biological products based on Trichoderma are available in the international market. However, Trichoderma-based products are not available in Sri Lanka. If native strains of Trichoderma can be isolated from the environment and tested for their antifungal activity against common phytopathogenic fungi, such isolates can be used to control pathogens. Therefore, the present study was conducted to assess the antagonistic activity of Trichoderma isolates on three selected postharvest pathogenic fungi of common fruit species in Sri Lanka, namely Colletotrichum musae, Colletotrichum acutatum and Botryodiplodia theobroma.
Three soil samples were collected from the premises of the University of Peradeniya and another soil sample was collected from a tea estate in Kandy. Soil samples were suspended separately in sterile distilled water and suspensions were filtered and used to make a dilution series <formula>. One ml of each dilution was spread on a Potato Dextrose Agar (PDA) plate. After three days of incubation at room temperature, Trichoderma colonies were identified by observing the colony and conidial morphology. Ten pure cultures of Trichoderma isolates were recovered and labeled A to J. Pure cultures of postharvest pathogenic fungi, C. musae, C. acutatum and B. theobromae, were obtained from the Plant Pathology Laboratory, Department of Botany, University of Peradeniya. Suspensions of conidia were prepared from fully grown cultures of Trichoderma isolates, C. musae and C. acutatum. The concentration of conidia suspensions of Trichoderma isolates was adjusted to <formula> and the concentration of conidia suspensions of the two pathogenic fungi was adjusted to <formula>. For B. theobromae mycelium discs were picked from the fully grown cultures as spore formation was minimal. A bioassay was conducted to test the antagonistic activity of Trichoderma on three fungal pathogens. Two wells were cut on each PDA plate using a one cm diameter cork borer. In each plate, one well was filled with 25 μl of Trichoderma conidial suspension and the other well was filled with 200 μl of conidial suspension of either C. musae or C. acutatum. For B. theobromae, a mycelium disc was placed in the well. After incubation, the diameter of Trichoderma colony and the pathogenic fungal colony was measured daily for seven consecutive days.
With Trichoderma isolates C, D and E, C. musae colonies stopped growing after four days of incubation and these Trichoderma isolates started to grow over C. musae colonies and the entire plates were covered with Trichoderma isolates on the seventh day, inferring the effectivity of isolates C, D and E against C. musae. The isolate G started to grow over C. acutatum colony after five days and was considered as effective against C. acutatum. Even though, all the isolates except G, started to grow over on B. theobromae, none of them had a significant effect. The Trichoderma isolates A, B, F, H, I and J did not exhibit a significant effect against any of these three pathogenic fungi. The Trichoderma isolates with antifungal activity must be further studied to formulate them as biopesticides and to understand their mode of action
Description
Keywords
ANTAGONISTIC , Trichoderma , PATHOGENIC FUNGI , Colletotrichum musae , Colletotrichum acutatum , Botryodiplodia theobromae
Citation
Peradeniya University Research Sessions Purse 2012, Book of Abstractsm University of Peradeniya, Sri Lanka, Vol-17, July.4.2013 P 245