Evaluation of herbicides for weed control in Darjeeling tea.
Field trials were conducted at Kurseong in 1983-87 to determine the efficacy of the following herbicide treatments for weed control in tea, in comparison with the estate practice of weed slashing: oxyfluorfen at 0.37 kg/ha (pre-em.); 2,4-D at 0.96, 1.2 and 1.8 kg (post-em.); dalapon at 3.82, 4.42 and 5.1 kg (post-em); paraquat at 0.22, 0.36 and 0.43 kg (post-em.); and glyphosate at 0.61, 0.92 and 1.23 kg (post-em.). The major weeds were Polygonum runcinatum, P. alatum, P. microcephalum, Drymaria cordata, Borreria articularis, Ageratum conyzoides, Commelina benghalensis, Oplismenus compositus, O. burmannii and Panicum colonum [Echinochloa colonum]. Glyphosate was the most effective treatment for control of the weeds, particularly at 0.96 and 1.23 kg where weed population was reduced to 5 and 3 weeds/plot, resp., compared to 36.8 weeds with the estate practice. Pre-em. applications of oxyfluorfen reduced the weed population to 6.1 weeds/plot, but it was reported that this treatment left the soil surface barren and led to erosion of top soil. Tea yields were highest with glyphosate treatments, with 0.61, 0.92 and 1.23 kg giving av. yields of 753.2, 711.5 and 721.2 kg/ha, resp., compared to 555.5 kg/ha with the estate practice.