Evaluation of preemergence applications of KIH-485, s-metolachlor CGA-154281, and smetolachlor atrazine CGA-154281 for crop phytotoxicity and weed control in corn, Nashua, IA, 2003

摘要

The purpose of this study was toevaluate various preemergence applied rates of KIH-485 and s-metolachlor & CGA-154281 for cropphytotoxicity and weed control in corn. The soil was a Floyd, Kenyon, Ostrander, and Clyde loam with apH 6.65 and 5.9% organic matter. The experimental design was a randomized complete block with threereplications and plots were 10 by 25 ft. The 2002 crop was soybean. Tillage included a spring fieldcultivation. Fertilization included 135 lb/A actual N applied as anhydrous ammonia. Crop residue on thesoil surface was 12% at planting. “NK hybrid 45-A6Bt” corn was planted 1.75 inches deep on May 21, at33,674 seeds/A in 30-inch rows. Preemergence (PRE) treatments were applied on May 23 at 20 gpa and25 psi using flat fan nozzles. Conditions on May 23 were: air temperature 18 C, soil temperature at the4-inch depth 16 C, 3 mph wind, 20% cloud cover, 67% relative humidity. Weed species number per ft2occurring in the untreated control included: giant foxtail zero to two plants; velvetleaf less than one plant;common waterhemp zero to one plant; common lambsquarters zero to one plant. May rainfall included:1.25, 0.06, 0.24, 0.7, 0.7, 0.04, 0.19, 0.07, 0.06, 0.27, 0.17, 0.02, and 0.2 inches on May 4, 5, 6, 7, 8, 9,10, 11, 13, 14, 22, 28, and 30, respectively. Total rainfall for May was 3.97 inches. June rainfallincluded: 0.15, 0.06, 1.76, 0.78, 0.46, 0.06, 0.12, 0.03, 0.33, 1.81, 0.01, 0.09, and 0.04 inches on June 2,4, 6, 7, 8, 9, 10, 13, 24, 25, 26, 27, and 28, respectively. Total rainfall for June was 5.7 inches. Julyrainfall included: 2.47 inches and 0.34 inches from July 1 through 15 and 16 through 31, respectively.Total rainfall for July was 2.81 inches. Rainfall total for August was 0.44 inches.