Effciency of Selected Herbicides for Tea Plantations

Abstract

Comparisons were made of a range of herbicides and rates of herbicide application with hand weeded and non-weeded treatments in a tea plantation at Mae Tang, Chiang Mai in July 1983. The herbicide treatments were atrazine at 2.25 kg a.i./ha, ametryne at 3.375 kg a.i./ha, diuron at 4.50 kg a.i./ha , paraquat at rates of 0.25 , 0.50 and 0.75 kg a.i./ha, paraquat at rates of 0.25 , 0.50 and 0.75 kg a.i./ha, glufosinate - aammonium at rates of 10, , 1.5 and 2.0 kg a.i./ha, fluazifopbutyl 25% E.C. and 35% E.C. at rates of 0.25, 0.35 , 0.37 and 0.50 kg a.i./ha, and the three herbicides MCPA, diuron and amitrole in combination at different rates as follows, 1.0 + 1.5 + 2.97 kg a.i./ha, 1.5 + 2.25 + 4.45 kg a.i./ha and 2.0 + 3.0 + 5.94 kg a.i./ha. The tea tree plantation was four years old with trees on a 60 x 90 cm spacing. Plot size was 3 m x 3.6 m with treatments arranged in a randomized complete block design with three replications.
Pre-emergence application of the herbicides atrazine, ametryne and diuron at rates of 2.25 , 3.375 and 4.50 kg a.i./ha respectively, all gave satisfactory weed control, however, the diuron treatment gave the longest control, a period of two months. Glyphosate at 3.0 kg a.i./ha, glufosinate - ammonium at 2.0 kg a.i./ha and the combined treatment of MCPA + diuron + amimonium at 2.0 kg a.i./ha and the combined treatment of MCPA + diuron + amitrole at 2.0 + 3.0 + 5.94 a.i./ha when applied post - emergence gave better weed control than the lower rates of application.
Germination of Imperata cylindrica, Cyperus rotundus and eleusine indica was not controlled by the pre-emergence applications of atrazine, ametryne or diuron. Only glyphosate at 2.0 kg a.i./ha and glufosinate- ammonium at 1.5 kg a.i./ha, when applied post emergence, gave satisfactory control of these three species.
There was no evidence of herbicide phytotoxicity to the tea in the experiment.