Abstract
The effectiveness of Trichoderma atroviride, T. asperellum, T. harzianum, against targeted tea disease causing pathogen, Fusarium solani (dieback), Beauveria bassiana against tea mosquito (Helopeltis theivora), and Metarhizium anisopliae against the red spider mite, Oligonychus coffeae Nietner, and the live wood eating termite (Microcerotermes beesoni Snyder), respectively were evaluated under laboratory and field conditions. The Trichoderma isolates showed effective control of F. solani (64.6 to 71.7%) under laboratory conditions, while the wettable powder (WP) formulation could reduce dieback disease incidence (57.1 to 77.7%) over control, under field conditions. The post prune application of Trichoderma asperellum on light pruned (LP) and application of T. asperellum as well as T. harzianum on deep skiffed (DS) tea fields showed a significant growth promotional response. The treated bushes could produce an average number of 421.2 and 398.4 shoots when it was applied 7.5 and 5.0% (w/v), respectively, which was higher than the number of shoots recorded in the control plots (259.4). The antagonist also induced comparatively higher shoot length (6.85–7.99 cm) than the untreated control plots (5.13–6.38 cm). The B. bassiana isolates (2 × 109 conidia/ml) exhibited 71.5 to 93.0% control of 2nd instar nymphs of H. theivora under in vitro conditions. However, addition of different adjuvants resulted in enhanced mortality. Under field conditions, the highest reduction of tea mosquito population of 52.3% was noted when B. bassiana (1 × 109cfu/ml) was sprayed along with Tween 20 plus and crude sugar. However, the wettable powder formulation of this EPF along with jaggery reduced the insect incidence. The M. anisopliae effectively controlled the red spider mite to the tune of 46.3 to 63.8% under laboratory conditions, while the wettable powder formulation of this isolate was more effective against the termite, resulting in the reduction of infestation to the tune of 84.2% under field conditions.
Highlights
Tea (Camellia sp.) is one of economically important plantation crops of India
The biological control agents (BCAs) like the species of Trichoderma, Beauveria, and Metarhizium are reported to be safer and promising components of integrated pest and disease management (IPDM) strategies, which have been adopted in various crops including tea (Hall and Papierok 1982)
Pathogen was identified as Fusarium solani, which produced cream-colored colonies with pinkish pigmentation on potato dextrose agar (PDA)
Summary
Tea (Camellia sp.) is one of economically important plantation crops of India. It is perennial in nature and provides favorable micro as well as macroclimate for thriving of different insect pests and fungal diseases, which together cause enormous crop loss in terms of quantity and quality. Synthetic agrochemicals have been used for the management of these pests and diseases. They provide efficient control for longer period; their frequent and injudicious application had definitely invited numerous other associated problems such as environmental pollution, development of pesticide resistance in insects, and unwanted pesticide residues in made tea (Roy et al 2011).
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