Trichoderma asperellum as a promising mycofungicide for managing the dieback disease of tea Camellia sinensis (L.) Kuntze

Background: The dieback disease of tea caused by Fusarium solani is one of the major constraints in determining its production and quality. Genus Trichoderma is a promising biocontrol agent to control the dieback without any residual effect and is the most suitable option for integrated disease management approach. A few local Trichoderma spp were isolated from tea rhizosphere of the Dooars zone and preliminary identified. Based on dual culture bioassay, the most efficient isolate got re-identified from well reputed national institutes and its liquid formulation (2% Aqueous Suspension) was prepared. Different concentrations of this formulation, T. harzianum and Hexaconazole were evaluated for the control of dieback disease and other parameters for two seasons in three zones under field conditions. Results: The fungal antagonist (KBN-29) was identified as T. asperellum based on characteristics such as regular mycelial branching, typically paired conidiophores with straight phialides and globose to sub-globose shaped conidia. It had the maximum control of dieback pathogen in lab experiment. Spray of T. asperellum formulation at 1200 and 1000 ml/ha concentration conferred comparatively better disease control and enhanced the yield of green tea leaves. The formulation was safe to non-target beneficial insects in all three zones without any phytotoxicity to tea leaves at 4, 8, and 16ml/L concentrations.ConclusionsThe present study confirms that T. asperellum 2% AS formulation was significantly superior in managing the dieback disease of tea plantations in Darjeeling, Dooars, and Assam zones at concentration of 1200 followed by 1000 ml / ha during both seasons. The maximum made tea yield was achieved in plots treated with T. asperellum at 1200 followed 1000 ml/ha. This formulation was safe to beneficial insects viz., C. carnea, O. javanus, and S. gilvifrons, furthermore it was not phytotoxic to tea leaves at 4 to 16ml/L concentrations.

Trichoderma asperellum as a promising mycofungicide for managing the dieback disease of tea (Camellia sinensis)

Background: The dieback disease of tea caused by Fusarium solani is one of the major constraints in determining its production and quality. Genus Trichoderma is a promising biocontrol agent to control the dieback without any residual effect and is the most suitable option for integrated disease management approach. A few local Trichoderma spp were isolated from tea rhizosphere of the Dooars zone and preliminary identified. Based on dual culture bioassay, the most efficient isolate got re-identified from well reputed national institutes and its liquid formulation (2% Aqueous Suspension) was prepared. Different concentrations of this formulation, T. harzianum and Hexaconazole were evaluated for the control of dieback disease and other parameters for two seasons in three zones under field conditions.Results: The fungal antagonist (KBN-29) was identified as T. asperellum based on characteristics such as regular mycelial branching, typically paired conidiophores with straight phialides and globose to sub-globose shaped conidia. It had the maximum control of dieback pathogen in lab experiment. Plots sprayed with T. asperellum formulation at 1000 and 1200ml/ha concentration conferred better disease control and enhanced the yield of green leaves. The formulation was safe to non-target beneficial insects in all three zones without any phytotoxicity to tea leaves at 4, 8, and 16ml/L concentrations.Conclusions: The present study confirms that T. asperellum 2% AS formulation was significantly superior in managing the dieback disease of tea plantations in Darjeeling, Dooars, and Assam zones at concentration of 1200 followed by 1000 ml / ha during both seasons. The maximum made tea yield was achieved in plots treated with T. asperellum at 1200 followed 1000 ml/ha. This formulation was safe to beneficial insects viz., C. carnea, O. javanus, and S. gilvifrons, furthermore it was not phytotoxic to tea leaves at 4 to 16ml/L concentrations.

Trichoderma Asperellum as A Promising Mycofungicide for Managing The Dieback Disease of Tea (Camellia Sinensis)

Background: The dieback disease of tea caused by Fusariumsolani adversely affects its production and quality. Genus Trichoderma is a promising biocontrol agent to control it without any residual effect and most suitable for inclusion into an integrated disease management approach. Isolation of Trichoderma from rhizosphere soil of the Dooars zone was done. It was identified as T. asperellum based on its cultural characters and DNA fingerprinting. A liquid formulation (2% Aqueous Suspension) was prepared from it and bio-efficacy was evaluated under field conditions for the control of dieback disease and other parameters for two seasons in three zones. Its different concentrations, T. harzianum, and Hexaconazole were included in the study. Results: The fungal isolate (KBN-29), identified as T. asperellum, was found nearest to the isolate TV-3 (Genebank-KX538814.1) with 99% similarity. Plots treated with T. asperellum 2% AS at 1000 and 1200ml/ha concentration gave better disease control as the yield of green leaves as compared to Hexaconazole 5% EC. The formulation was safe to non-target beneficial organisms’ in all three zones without any phytotoxicity to tea leaves at 4, 8, and 16ml/L concentrations.Conclusions: The present study confirms that the developed liquid formulation of T. asperellum 2% AS was found significantly superior for the management of dieback disease of tea plantations in Darjeeling, Dooars, and Assam zones when used at concentrations of 1200 and 1000 ml followed by 800 and 600 ml/ha during both seasons. The maximum made tea yield was recorded in plots treated with T. asperellum at 1000 and 1200ml/ha followed by Hexaconazole 5% EC. The T. asperellum 2% AS was observed to be safe for non-target beneficial organisms viz., C. carnea, O. javanus, and S. gilvifrons. The developed T. asperellum 2% AS formulation was not phytotoxic to tea leaves at 4, 8, and 16ml/L concentrations.

Occurrence of severe mosaic disease of potato and study on effect of different treatments under integrated disease management approach

Occurrence of severe mosaic disease of potato caused by <italic>Potato virus Y</italic> (PVY) in all the potato growing areas of Jorhat district of Assam, India was determined by DAS-ELISA. An integrated disease management experiment for severe mosaic disease was carried out at the Experimental farm of Assam Agricultural University, Jorhat in field condition comprising spraying of commercial neem formulation, application of mineral oil, yellow sticky trap, bio fumigation with rape seed plants one month before planting, bio fumigation with cabbage plants one month before planting, spraying of <italic>Metarrhizium anisopliae</italic> and spraying of insecticides as treatments. The treatment T₄ (bio fumigation with rapeseed plants one month before planting) followed by T₂ (four application of mineral oil @ 5 ml/lit at 15 days interval) was found to be most effective in reduction of disease incidences, vector population as well as yield than the other treatments.