Abstract
Dicamba plus glyphosate tank mixture have been largely adopted for postemergence weed control after the development of dicamba-tolerant crops. Ammonium sulfate is commonly used as water conditioner (WC) to increase glyphosate efficacy, but its use is restricted for dicamba herbicides. The use of non-AMS water conditioner and other adjuvants could be a way to optimize efficacy of this tank mixture while mitigating herbicide off-target movement. The objective of this study was to determine the physical–chemical properties and droplet size distribution of dicamba and glyphosate solutions with and without non-AMS WC alone and tank mixed with other adjuvants and evaluate the response of weed species to these solutions under greenhouse and field conditions. The adjuvants mostly increased density and viscosity and decreased contact angle and surface tension of herbicide solutions. In presence of WC, except for the adjuvants containing drift reducing agent, Dv0.5 decreased with the addition of adjuvants. Under greenhouse conditions, biomass reduction increased up to 47 and 33 percentage points for velvetleaf and c. waterhemp when adjuvants were added to solutions without WC, respectively. No increase in control of horseweed and Palmer amaranth was observed with the use of adjuvants under field conditions.
Highlights
The introduction of glyphosate-resistant (GR) crops in 1996 has largely contributed to the adoption of glyphosate in the United States
Solutions containing adjuvants NIS1, non-ionic surfactants (NIS)-DRA2, NISH4, NISH5, and NISH6 presented density of 1.0070 g cm−3 compared to 1.0060 g cm−3 for dicamba plus glyphosate tank mixture (DpG) alone which corresponds to 0.1%
Previous studies reported that density, viscosity, surface tension, contact angle, droplet size, and droplet evaporation of the spray solution can change with the addition of adjuvants to the spray solution [43,44,45,46]
Summary
The introduction of glyphosate-resistant (GR) crops in 1996 has largely contributed to the adoption of glyphosate in the United States. In 1996, the estimated used amount of this herbicide was 11 million kg compared to 136 million kg in 2016 [1]. Glyphosate is the most widely used herbicide in the country [2]. As a consequence of the overuse of this herbicide for a prolonged period of time, high occurrence of GR weed populations has been reported across the country. There are 17 GR weed species reported in the United States [3]. In 2015, the USDA [4] estimated a reduction in financial returns of 66%
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
