Single applications of Cotoran 4L at 0.5 and 0.75 lb ai/A, Probe 75WDG at 0.25 and 0.375 lb ai/A, and DPX-T9595 75WDF at 0.0625 and 0.125 oz ai/A were applied over-the-top (OT) to cotton DES 119 plants at cotyledon to one true leaf, three true leaves, and six to eight true leaves. The area was also treated with Zorial^® 8ODF 0.56 lb ai/A PPI on March 17 and Zorial 80DF 0.56 lb ai/A plus Meturon^® 4L 1.125 lb ai/A PRE. The area was cultivated to a 12-inch band 3 weeks after each OT herbicide application was made and was repeated as needed throughout the rest of the season. Half each plot was hoed from 46 to 56 days after treatment while the remaining half contained some weeds throughout the growing season.

Seed cotton yield without herbicides averaged 2346 lb/A. Where herbicides were applied, a significant herbicide by rate by application time interaction occurred. Yield was lowest (a 568 lb/A decrease from the control) when Cotoran at 0.5 lb ai/A was applied to six- to eight-leaf cotton. Yields from applications of herbicides applied to two- and four-leaf cotton were not different. Applications of Probe at either rate, Cotoran at 0.75 lb, or DPX-T9595 at either rate were not different at P=.05 when applied at the six- to eight-leaf stage. Seed cotton yields from areas where weeds were removed after 46 to 56 days also resulted in a herbicide by rate by application time interaction. Lowest yield occurred again where Cotoran was applied at 0.5 lb/A to six- to eight-leaf cotton. Highest yield occurred with this same herbicide and application rate to two-leaf cotton. In general no conclusive yield information was obtained from the herbicides, rates, and times of application used in 1988.

Cotton height, measured 2 weeks after treatments applied to two-leaf plants, resulted in tallest plants obtained with the high rate of DPX-T9595 and shortest plants obtained with the high rate of Probe. When cotton plants were measured 14 days after application to the four-leaf stage of cotton, tallest plants were obtained with either rate of DPX-T9595 and shortest plants were obtained with the high rate of Cotoran. Cotton plant height differences when measured 14 days after application to the six- to eight-leaf stage resulted in no significant differences between herbicides or rates. The maximum height difference between the shortest and tallest plants at this growth stage was about one inch. When cotton height was expressed as a percentage of the untreated control at 14 days after treatment, there was a herbicide by application time interaction. Cotoran at the four-leaf stage produced significantly shorter plants than DPX-T9595 applied at the four-leaf stage or Probe applied at the six- to eight-leaf stage.

Cotton stand was not affected by any of the treatments.

When plots were hoed on June 30 (48 days after treatment of the two-leaf cotton plants) a hoe-time of 4.01 hours/A occurred with an untreated control. Hoe time ranged up to 5.12 hours/A when Probe was applied at 0.375 lbs ai/A OT of two-leaf cotton. There were no significant differences among treatments at the June 30 hoeing. Subsequent hoeing of plots treated OT at four-leaf or at six-leaf stages resulted in hoe times of a low of 5.20 hours/A with Cotoran at 0.5 lb ai/A applied OT to six- to eight-leaf cotton (46 days after treatment) and a high of 7.51 hours/A with Probe at 0.25 lb ai/A applied to 4-leaf cotton (56 days after treatment). Again, there were no significant differences among hoe times for these treatments.

Low infestation levels of entire leaf/ivyleaf, pitted, and palmleaf morningglory, slender amaranth, smooth pigweed, and hemp sesbania did not affect cotton yield.