Timing of soil-active herbicide incorporation with sprinkler irrigation

摘要

A question often asked by growers is how long can a soil-applied herbicide remain on the soil surface before it is incorporated into the soil, either mechanically or with overhead water, and still be effective? Some labels have, such as the Eptam herbicide label, have instructions on how soon a herbicide must be incorporated, but other soil-active herbicides do not. A field experiment was conducted at the University of Idaho Research and Extension Center near Kimberly, Idaho to determine how soon soil-active herbicides applied with glyphosate for weed control in sugar beet need to be incorporated with sprinkler irrigation before they lose their effectiveness. The experimental design was a 4 by 5 factorial randomized complete block with four replications. Five herbicides treatments, consisting of acetochlor, dimethenamid-P, EPTC, ethofumesate, s-metolachlor and glyphosate alone were applied 9, 6, 3, and 0 days before incorporation (DBI) with overhead sprinker irrigation. All of these herbicide treatments, except glyphosate alone, were applied in combination with glyphosate at the 4-leaf sugar beet growth stage. These applications were applied sequentially to glyphosate alone at 0.77 lb ae/A applied at the 2-leaf growth stage. Individual plots werefour rows by 30 ft. Soil type was a Portneuf silt loam (19% sand, 60% silt, and 21% clay) with a pH of 8.3, 1.3% organic matter, and CEC of 28.4-meq/100 g soil. 'Holly Hybrid SX1502RR' sugar beet was planted April 14, 2014, in 22-inch rows at a rate of 60,590 seed/A. Common lambsquarters (CHEAL), kochia (KCHSC), redroot pigweed (AMARE), hairy nightshade (SOLSA), common mallow (MALNE) and green foxtail (SETVI), were the major weed species present. Herbicides were applied broadcast with a CCh-pressurizedbicycle-wheel sprayer calibrated to deliver 15 GPA using 11001 flat fan nozzles. Additional environmental and application information is given in Table 1. Weed counts by species were taken on July 1 and 14; 14 and 28 days after the herbicide incorporation (DAHI). The two center rows of each plot were harvested mechanically on October 7.