Efficacy of various fungicides and indigenous biocontrol agents against red root rot disease of tea plants

摘要

An experiment was conducted to study the effectiveness of contact, systemic and botanical fungicides, and indigenous biocontrol agents in controlling red root rot disease of tea plants. In general, all tested bioagents, the combination of Pseudomonas fluorescens and Trichoderma atroviride reduced red root disease incidence recorded in two consecutive field experiments. Among the fourteen treatments tested, soil drenching of systemic fungicides was superior but similar to the combination between P. fluorescens and T. atroviride. In contrast, the maximum green leaf yield and plant growth was achieved when soil application of biocontrol agents was carried out. However, the performance of these biocontrol agents under various combinations was on par with systemic fungicides, but superior to botanical fungicides. Correspondingly, the physiological and biochemical parameters were also greatly increased in plants in several treatments when compared to untreated control. The disease increased from 31.5 % to 40.0 % in untreated control plots and those plants were unhealthy in terms of leaf yellowing, stunted growth with heavy flowering, drying of branches and sudden death of bushes. The tea quality parameters were significantly improved in treated plants including total liquor colour, thearubigins, theaflavins, highly polymerized substance and caffeine contents.