Assessing Even Flat-Fan Nozzles for Spot Spray Herbicide Applications

Authors

Thiago H. Vitti, University of Nebraska-LincolnFollow

First Advisor

Christopher A. Proctor

Committee Members

Greg Kruger, Nevin Lawrence

Date of this Version

8-2024

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Agronomy

Under the supervision of Professor Christopher A. Proctor

Lincoln, Nebraska, August 2024

Comments

Copyright 2024, Thiago H. Vitti. Used by permission

Abstract

Herbicide efficiency in row-crop agriculture can be improved using precision technologies for controlling weeds and minimize agronomic, economic, and environmental impacts. Site-specific weed management technologies, such as spot-sprayers, allow herbicides to be sprayed only where weeds are present in the field. Understanding application parameters and their influence on weed control for site-specific spot-spray applications is essential. This research involved laboratory and greenhouse studies to investigate the coverage and coefficient of variation (CV) of even flat-fan spray nozzles under different spot-spray application scenarios, as well as the effect of weed size and application method on the control of various weed species using a pulse width modulation system to control herbicide rate. Adjusting the nozzle angle from 0° to 30° rearward resulted in a mean reduction of 7% in spray coverage for both AI6502E and TP6502E nozzles. This adjustment also led to a 6% decrease in CV for the AI6502E nozzle, while it had no impact on the TP6502E nozzle CV. Additionally, a 25% average increase in CV was observed when the boom height was reduced from 75 cm to 25 cm. Greenhouse research revealed that weeds exhibited high sensitivity to 2,4-D, dicamba, and clethodim, regardless of weed size and application method. In contrast, glyphosate and glufosinate provided superior control when applied at early growth stages, underscoring the importance of early postemergence herbicide management for these herbicides in variable-rate applications. The research findings from both studies enhance our understanding of how various application parameters can influence spot-spray operations and the sensitivity of weeds to different herbicides at different growth stages. This knowledge is crucial for establishing effective herbicide variable-rate strategies, optimizing weed control, and minimizing herbicide use.

Advisor: Christopher A. Proctor