Spray Characterization and Herbicide Efficacy as Influenced by Pulse-Width Modulation Sprayers

Pesticide applications are a heavily scrutinized facet of today’s agricultural industry, and a concerted effort to optimize each application needs to be implemented. More precise and efficient pesticide applications are necessary to meet regulatory demands and increase economic efficiency through reduced pesticide inputs. Current pesticide application methods using precision technologies, including pulse-width modulation (PWM) sprayers, can assist with these goals. However, vast advancements in pesticide formulations, adjuvants, and nozzles, as well as the increasing popularity of PWM systems, have only increased the need for applied PWM and weed science research. Additionally, efforts have been placed on increasing spray droplet size to reduce particle drift, but this practice has led to reduced herbicide efficacy. Therefore, identifying an optimum herbicide droplet size which can reduce particle drift while simultaneously maintaining efficacy is a necessity. The objectives of this research were to: (1) identify the influence of application parameters on droplet size, droplet exit velocity, nozzle tip pressure, and spray pattern uniformity from a PWM sprayer, (2) create best use PWM recommendations to optimize pesticide applications from these sprayers, (3) investigate the effect of spray droplet size and carrier volume on the efficacy of multiple herbicide solutions, (4) establish novel weed management recommendations based on an optimum droplet size, and (5) determine the plausibility of using PWM sprayers in site-specific weed management strategies. The results of this research have led to more precise PWM sprayer operation through clear and concise best use recommendations. The capability of PWM sprayers to make precise and uniform applications can assist with the reduction of spray particle drift and increase the overall application effectiveness. Additionally, site-specific weed management strategies were effectively established and optimum herbicide droplet sizes were estimated across a wide range of geographies and weed species. Although, convoluted interactions were identified between droplet size, carrier volume, and other application parameters in regards to their effect on herbicide efficacy. As a result of this research, applicators can more effectively utilize PWM sprayers, reduce herbicide inputs, mitigate spray particle drift, and reduce the selection pressure for the evolution of herbicide-resistant weeds. Advisor: Greg R. Kruge

Sediment oxygen demand and its effect on dissolved oxygen in a cutoff meander of the Kaskaskia River

This study was designed to assess the relationship of sediment oxygen demand and dissolved oxygen in a cutoff meander of the Kaskaskia River. The results of the study should be useful to agencies such as Departments of Conservation, Corps of Engineers and the Environmental Protection Agency when assessing the impact of stream channelization on cutoff meanders of channelized streams. Cross-sectional profiles were used to determine area and total water volume in the meander. When stagnant or no-flow conditions prevailed, anoxic conditions created by sediment oxygen demand were observed in a significant part of the water in the meander. When no-flow conditions prevailed during summer months, as much as 25% of the water in the meander became anoxic while 65% fell below 5.0 mg/l. Sediment oxygen demand rates were more closely related to temperature than to sediment consistency or benthic macroinvertebrate numbers. Ambient sediment oxygen demand measured during the summer was almost three times greater than demand measured during the fall. While sediment oxygen demand in the channelized portion of the river was higher than in some stations in the meander, reaeration resulting from flowing water in the channel was sufficient to prevent anoxic conditions from developing.U.S. Department of the InteriorU.S. Geological SurveyOpe

Benthic sediment conditions and remediation alternatives for Horseshoe Lake, Alexander County

"Office of River Water Quality.""February 1997.""Office of Surface Water Resources: Systems, Information & GIS.""Contract Report 607"--Cover."Prepared for the Division of Fisheries, Illinois Dept. of Natural Resources.

Evaluation of reaeration efficiencies of sidestream elevated pool aeration (SEPA) stations

"Prepared for the Metropolitan Water Reclamation District of Greater Chicago"--Cover

Correspondence to M. Rebecca Boggs, dates unknown

Correspondence to M. Rebecca Boggs, dates unknown. Box 2, folder 9.https://digitalcommons.wofford.edu/littlejohnboggs/1019/thumbnail.jp

An Assessment of Bottom Sediment Conditions in the Illinois River in the Vicinity of Pekin Combined Sewer Overflows

published or submitted for publicationis peer reviewedOpe

Sediment oxygen demand studies of selected northeastern Illinois streams

ISWS/CIR-129/78.Includes bibliographical references (p. 49-50)

Measurements of Sediment Oxygen Demand Characteristics of the Upper Illinois Waterway

Oxygen demand characteristics of bottom sediments for a 113-mile reach of the Upper Illinois Waterway were measured in situ at 22 locations in order to assess the effects of such demand on the dissolved oxygen resources of the overlying water. For the measurements of sediment oxygen demand (SOD), a bottom sampler was specially designed to entrap and seal a quantity of water at the river bottom. Changes in dissolved oxygen (DO) concentrations within the entrapped water were recorded by a DO probe fastened in the sampler. SOD values for 20 undisturbed bottom locations ranged from 0.56 to 5.00 grams per square meter per day (g/m2/day), and values at 2 disturbed locations were 6.45 and 8.08 g/m2 /day. The oxygen demands of sediments in many parts of the waterway are sufficiently high to impose a significant demand on the DO content of the overly ing water. In addition to SOD measurements, 172 bottom samples were collected, described in detail, and analyzed for percent organic and dried solids content. Expressions for the relationship between these percentages and the SOD rates were developed and used to estimate probable SODs at the various sampling sites. Subsequent charts of the river bed depict the ranges of SOD values useful in engineering analyses of the waste assimilative capacity of the Upper Illinois Waterway.publishedpeer reviewedOpe

An Assessment of Illinois River Bottom Sediments in the Vicinity of the Havana Combined Sewer Overflows

published or submitted for publicationis peer reviewedOpe