Rate by timing field studies were conducted in 1988 and 1989 using KIH-8921 at the Dean Lee Research Station at Alexandria, the Northeast Research Station at St. Joseph, and the Red River Research Station at Bossier City, Louisiana. Four rates of KIH-8921 used were 0.075, 0.10, 0.15, and 0.20 lb ai/A. Four timings evaluated were preemergence (PES) and postemergence (POT) 1, 2, and 3. The standards used for PES was Cotoran at 1.2 lb and for all POT's was Cotoran + MSMA at 0. 8 + 1. 0 lb. Weed heights ranged from 1-5 in at POT-1, 2-8 in at POT-2, and 3-12 in at POT-3. Experimental design was a three-factor factorial with four replications in a randomized complete block design. Treatments were sprayed in 10- to- 20 gal/A aqueous solution with 0.25% v/v nonionic surfactant.

Using only the 0.10-lb rate as the predicted use rate the data was averaged across years and locations. KIH-8921 applied at POT-1 gave 80% and above control of hemp sesbania, common cocklebur, pigweed, smell melon, seedling johnsongrass, prickly sida, wild poinsettia, and spotted spurge. Morningglory control approached 80% at this timing and also POT-2. Application at POT-2 and -3 also gave acceptable control of sensitive weeds such as hemp sesbania and common cocklebur. PES applications gave 80% and above control of smell melon, seedling johnsongrass, wild poinsettia, spotted spurge, and annual grasses. Less than 40% control of hophornbeam copperleaf was obtained with KIH-8921 at any timing and rate; however, Cotoran at PES or Cotoran + MSMA at POT-1 controlled this weed. Yields of weed-free plots indicated significant reductions when KIH-8921 was applied PES at 0.20 lb and Cotoran + MSMA at POT-3 at only one location.