Aerial application methods for control of weed species in fallow farmlands in Texas

Authors: Martin, Daniel - Dan; Latheef, Mohamed - Ab; LOPEZ, JUAN DE DIOS - Retired ARS Employee; Duke, Sara

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2020
Publication Date: 11/26/2020
Citation: Martin, D.E., Latheef, M.A., Lopez, J., Duke, S.E. 2020. Aerial application methods for control of weed species in fallow farmlands in Texas. Agronomy Journal. 10:11.

Interpretive Summary: Post-emergent weeds in major agronomic row crops cause $15B worth of yield loss annually in the United States. Field studies were conducted over two years which investigated the efficacy of commercially available aerial application technologies for control of winter weeds. The work established that charged glyphosate with electrostatic nozzles was equally effective in controlling weeds as conventional aerial nozzles at only 1/3rd of the spray application rate. This lower application rate, with equivalent control, will allow aerial applicators to be more productive and profitable while still achieving desired efficacy.

Technical Abstract: The objectives of this research were to evaluate aerial application technologies for the control of monocot and dicot weed species in farmlands left fallow until spring. Prolific growth of weeds, especially when followed by abundant rainfall, is common in Texas farmscapes during early winter and progresses into spring when farmers begin chiseling and disking operations for spring-seeded cropping. This would likely help facilitate low or no-till production agriculture through efficacious management of winter weeds. Glyphosate was applied using a fixed-wing aircraft with conventional hydraulic and electrostatically (ES) charged nozzles during year one. In year two, rotary atomiser nozzles were added as a treatment. Control plots were maintained during both years. The active ingredient rate for glyphosate was 0.4145 kg ae·ha-1. The spray application rates for the conventional and rotary nozzles were 28.1 L·ha-1 and 9.4 L·ha-1 for the ES charged on nozzle. Aerial and ground-based remote sensing and visual estimates quantified weed vigor and canopy health. Both the CP and the rotary atomiser nozzles were efficacious in suppressing weeds. ES charged on nozzles at 1/3rd of the spray rate of the CP and the rotary atomiser nozzles were equally effective in reducing weed vigor. More aerially applied replicated field research trials conducted over time and space are needed to unravel differences between nozzle technologies for controlling weed populations in Texas farmlands.