Efficacy and economics of light‐activated sensor‐controlled sprayer for site‐specific weed control

Abstract

AbstractAn increasing cost of controlling herbicide‐resistant weeds necessitates the development of cost‐effective weed control strategies in the semi‐arid U.S. Great Plains. Two separate field studies were conducted in 2013 and 2014 at the Montana State University Southern Agricultural Research Center near Huntley, MT to (1) evaluate a light‐activated sensor‐controlled (LASC) sprayer compared to a broadcast sprayer for effectiveness and cost savings for weed control in postharvest wheat (Triticum aestivum) stubble, and (2) determine the efficacy of LASC sprayer operated at two different speeds for weed control in fallow fields. Results indicated that both LASC and broadcast sprayers performed similarly for the effectiveness of a majority of herbicides tested on kochia [Bassia scoparia (L.) A.J. Scott] and prickly lettuce (Lactuca serriola L.). Paraquat alone or in tank‐mixture with linuron, and saflufenacil + 2,4‐D provided 93%–100% control of kochia, 98%–100% control of prickly lettuce, and reduced the total weed biomass by 75%–80% at 28 days after treatment (DAT), regardless of the sprayer used. A simple comparative economic analysis revealed that LASC sprayer reduced the overall chemical use by 23%–55% and resulted in cost savings of $5.83–$30.83 ha−1 across herbicide treatments. Herbicide efficacy was reduced up to 20% for kochia and prickly lettuce control when applied with LASC sprayer at a speed of 16 versus 8 km h−1. Altogether, these results indicate that the LASC sprayer can provide cost‐effective, site‐specific weed control in no‐tillage chemical fallow or postharvest wheat stubble.