Agronomy and Horticulture, Department of

 

First Advisor

Amit Jhala

Committee Members

Nicolas Cafaro La Menza, Stevan Knezevic

Date of this Version

7-2024

Document Type

Thesis

Citation

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

Major: Agronomy

Under the supervision of Professor Amit Jhala

Lincoln, Nebraska, July 2024

Comments

Copyright 2024, Adam Eric Leise. Used by permission

Abstract

Herbicide sprayers are becoming larger and more efficient in applications in crop fields. A precise and efficient herbicide application is advantageous in effective weed control. New precision sprayers were introduced in hopes of reducing the amount of herbicide applied. Greeneye Technology and John Deere have developed precision sprayers for the detection of weeds in crop fields, which come equipped with a dual tank system that allows for two different herbicides to be separated from tank to tip. The objectives of this study were to evaluate the broadleaf and grass weed control efficacy of spot spray (SS) technology when applied in spot application versus broadcast application as well as herbicide savings. Greeneye technology’s SS machine achieved similar control of palmer amaranth (amaranthus palmeri) (99%) and giant foxtail (setaria faberi) (94-99%) 21 days after POST. When using the John Deere SS machine in 2023, weed control of various broadleaves were similar when comparing SS against broadcast both 21 days after early-POST (A) and late-POST (B). Non-residual herbicide savings were much higher in 2022, achieving 87-94% savings, compared to the highest herbicide saved in 2023 of 5.4%. With early season applications of residual herbicides in 2022, and no residual herbicides applied in 2023, herbicide savings can be directly linked to weed pressure at application timing.

The objectives of the next two studies were to use the dual tank design to separate graminicides (clethodim and quizalofop-p-ethyl) from commonly applied POST herbicides in corn (2,4-d choline) and soybean (dicamba) to reduce antagonism. In soybean, the physical separation of herbicides in dual tank applications provided 71-76% higher control of volunteer corn than tank-mix treatments at 28 days after application. In corn, the separation of herbicides using a dual tank system did provide 93-99% volunteer corn control but was not significantly different from tank-mix treatments. The results from these studies suggest that a dual tank design may mitigate antagonism.

Advisor: Amit Jhala

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