Role of beneficial fungi in managing diseases and insect pests of tea plantation

The effectiveness ofTrichoderma atroviride,T. asperellum,T. harzianum, against targeted tea disease causing pathogen,Fusarium solani(dieback),Beauveria bassianaagainst tea mosquito (Helopeltis theivora), andMetarhizium anisopliaeagainst the red spider mite,Oligonychus coffeaeNietner, and the live wood eating termite (Microcerotermes beesoni Snyder), respectively were evaluated under laboratory and field conditions. TheTrichodermaisolates showed effective control ofF. 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 ofTrichoderma asperellumon light pruned (LP) and application ofT. asperellumas well asT. harzianumon 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). TheB. bassianaisolates (2 x 10(9)conidia/ml) exhibited 71.5 to 93.0% control of 2nd instar nymphs ofH. theivoraunder 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 whenB. bassiana(1 x 10(9)cfu/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. TheM. anisopliaeeffectively 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.