Bio efficacy of indigenous biological agents and selected fungicides against branch canker disease of (Macrophoma theicola) tea under field level.

Background: Branch canker caused by Macrophoma theicola is a major stem disease of tea plants (Camellia spp.). In tea plantations, this disease causes crop loss and it is one of the major limiting factor for yield stagnation. In very few instances it causes considerable damage in new clearings (about 3 or 4 years old) and large number of bushes have been killed. As there is no control measures for branch canker disease in south Indian tea plantation, this field study was conducted in naturally infected pruned tea field at UPASI Tea Research Institute (Good Agricultural Practice), Valparai, Tamil Nadu, India.

Methods: The chemical fungicides, biological agents and bio products were evaluated under naturally infected field of seedling plants for two consecutive disease seasons (2014-2015) and there was 11 treatments with three applications. All the treatments were carried out in the time of February-March and October-November (2014-2015). The two set of application was conducted per year. Each set contains eight rounds during the month of February-March as well as October-November (2014-2015). The chemical fungicides, biological agents and commercial bio products were measured as per UPASI- TRF, recommendation viz., COC (50 g/ha and 0.2 g/plot), Companion (20 g/ha and 0.08 g/plot), biological agent of Bacillus amyloliquefaciens, Tichoderma harzianum, Gliocladium virens and Beauveria bassiana (5 kg/ha and 20.8 g/plot) and bio product of Tari (1 L/ha and 4.2 ml/plot) and Tricure (1 L/ha and 4.2 ml/plot).

Results: The present investigation revealed the integrated application of Companion/Bacillus amyloliquefaciens showed superior control of branch canker disease followed by the treatment with Companion alone under field condition. Copper oxychloride/Bacillus amyloliquefaciens was moderately effective followed by Copper oxychloride. The significantly reduced canker size was recorded with treatment of Bacillus amyloliquefaciens followed by commercial organic fungicides of Tari (Organic Tea Special) and Tricure (0.03% Azadirachtin). The least canker size was observed with Gliocladium virens followed by Beauveria bassiana. Branch canker disease incidence was increased in untreated control plants when compared to treated plants.

Conclusion: Among these 11 treatments, the integrated treatment of companion at rate of 0.08 g and Bacillus amyloliquefaciens (20.8 g) showed the most significantly decreased canker size (DPL, 5.76) followed by another treatment with companion (0.08 g) (DPL, 4.11). The moderate reduction of canker size was observed by the treatment with Copper oxychloride (0.2 g)/Bacillus amyloliquefaciens (20.8 g) (DPL, 3.05) followed by the treatment of copper oxychloride alone (DPL, 1.74). Therefore, the integrated application of Companion/Bacillus amyloliquefaciens proved significantly effective in the management of branch canker disease under the field conditions.