Comparison of Herbicide Efficacy and Adjuvants Using a Conventional Sprayer and an Ultra-Low Volume Sprayer

Abstract

An Ultra-Low Volume (ULV) sprayer was developed to decrease spray volume needed for crop production pesticide applications. A field study was conducted at the University of Nebraska–Lincoln: West Central Research and Extension Center Dryland Farm near North Platte, NE in 2011 and 2012 to determine efficacy of herbicide active ingredients when applied by a ULV sprayer compared to a conventional sprayer. The effect of four drift reducing adjuvants on glyphosate efficacy with an ULV sprayer at two pressures was also evaluated. Ten active ingredients with each sprayer and an untreated check (21 total treatments) were arranged in a randomized complete block design with four replications. The ten herbicides chosen were glyphosate, glufosinate, 2,4-D ester, dicamba, atrazine, saflufenacil, mesotrione, chloransulam-methyl, sodium salt of bentazon, and clethodim. Additionally, four drift reducing adjuvants, a glyphosate check and an untreated check were arranged in a randomized complete block design with four replications. The four adjuvants selected were hydroxyethyl cellulose (HEC), polyethylene oxide (PEO), methylated soybean oil (MSO), and glycerin. Treatments were applied across a 12 row plot planted to six different plant species. Plant species used were non-glyphosate-resistant corn (Zea mays L.) non-glyphosate-resistant soybeans (Glycine max (L.) Merr.), amaranth (Amaranthus hypochondriacus L.), quinoa (Chenopodium quinoa Willd.), velvetleaf (Abutilon theophrasti Medik.), and green foxtail (Setaria viridis (L.) Beauv.). Treatments in both studies were analyzed for their relative particle size on a laser diffraction instrument. Five plants of each species per plot were harvested four weeks after application, dried for 48 h at 63°C and dry weights were recorded. The active ingredient study yielded no difference in efficacy between sprayer types across all six species in 2011 but was different in corn in 2012. Simple effect differences of treatment by sprayer type were observed in both years. The adjuvant study had no difference in glyphosate efficacy across the four adjuvants or the glyphosate check over the six species in 2011 and corn and soybean in 2012. Additionally, pressure did not affect efficacy across all treatments. The results indicate that the ULV sprayer is potentially an effective method for delivering herbicides.