Effect of simulated drift rates of roundup ultra (glyphosate), Buctril (bromoxynil), and Liberty (glufosinate) on growth and yield of conventional cotton

摘要

A field study was conducted in 1999 at the Macon Ridge Research Station in Winnsboro LA to determine the effect of Roundup Ultra (glypbosate), Liberty (glufosinate), and Buctril (bromoxynil) simulated drift rates on conventional cotton. The experimental design was a randomized complete block with a 3 (herbicide) X 7 (rates) X 3 (timing) factorial arrangement of treatments replicated four times. Plot size was 6.67' X 35'. Simulated drift rates of 0, 1/4, 1/8, 1116, 1132, 1164, and 1/128x of the labeled rate of Roundup Ultra (1.0 lb ai/A), Liberty (0.365 lb ai/A), and Buctril (0.5 lb al/A) were applied to STV 474 cotton at the 2, 5, and 9 node growth stage. Applications were broadcast with a handboom at 15 GPA. Drift to adjacent plots was eliminated by use of physical barriers between plots. Supplemental furrow irrigation as needed and standard weed, insect and fertility practices were utilized. Parameters measured included visual injury 14 days after each application timing (DAT), plant height 30 DAT (10 random plants/plot), whole plant dry weight 30 DAT (1 m section of row/plot), nodes above white flower (NAWF) (10 random plants/plot) mid-season, green and open boll (1 m section of row/plot) late season, final plant population prior to harvest, and seedcotton yield. Dry weight and height data are presented as a percent reduction from the nontreated control (0 rate). For ease of analysis, data were analyzed by herbicide and subjected to ANOVA and means separated by Tukey-Kramer at the 5 percent probability level.