Evaluation of crop phytotoxicity and weed control in corn with postemergence applied nicosulfuron rimsulfuron, atrazine, mesotrione and others, Ames, IA, 2002

摘要

The purpose of this study was to evaluate the crop safety and weed control potential of postemergence nicosulfuron & rimsulfuron applied alone, and tank-mixed with various rates of atrazine, and mesotrione. The soil was a Canisteo, Nicollet, Clarion, Webster, Hayden-Storden clay loam with a pH 7.05 and 4.0% organic matter. The experimental design was a randomized complete block with three replications and plots were 10 by 25 ft. The 2001 crop was soybean. Tillage included a fall chisel plowing andspring field cultivation. Fertilization included 125 lb/A actual N applied as urea. Crop residue on the soil surface was 12 percent at planting. "Pioneer hybrid 34B23" corn was planted 1.5 inches deep on May 7, at 27,700 seeds/A in 30-inch rows. Preemergence (PRE)and mid-postemergence (MPOST) treatments were applied on May 8 and June 7, respectively, at 20 gpa and 30 psi using flat fan nozzles. Conditions on May 8 were: air temperature 28 C, soil temperature at the 4-inch depth 18 C, 11 mph wind, 90 percent cloudcover, 71 percent relative humidity. Conditions on June 7 were: air temperature 29 C, soil temperature at the 4-inch depth 23 C, 12 mph wind, clear sky, 56 percent relative humidity. Corn growth was V4 to V5 and 10 inches tall. Weed species, size and number per ft~2 in the untreated control included: giant foxtail three to four leaves, 5 to 7 inch tall, fifteen plants; velvetleaf five to seven leaves, 4 to 8 inches tall, zero to five plants; common waterhemp numerous leaves, 4 to 8 inches tall, five toten plants; common lambsquarters numerous leaves, 3 to 6 inches tall, zero to ten plants; Pennsylvania smartweed two to six leaves, 3 to 8 inches tall, zero to one plants; and common cocklebur five to six leaves, 3 to 8 inches tall, zero to two plants.May rainfall included: 0.45, 0.01, 0.07, 2.60, 0.12, 0.19, 0.23, 0.09, 0.66 inches on May 1, 2, 5, 11, 15, 16, 23, 24, and 25, respectively. Total rainfall for May was 4.42 inches. June rainfall included: 0.54, 0.83, 1.41, 0.01, and 0.01 inches on June 2, 11, 12, 13, and 20, respectively. Total rainfall for June was 2.8 inches. July rainfall included: 4.8 inches and 0.46 inches from July 1 through 15 and 16 through 31, respectively. Total rainfall for July was 5.26 inches. Rainfall total for August was4.89 inches.