There is a growing interest in agricultural spray drone (ASD) use for herbicide application in managed turfgrass systems, which historically has precluded aerial application. Considering pesticide deposition accuracy is of utmost importance in managed turfgrass systems, a thorough examination of factors that influence ASD spray deposition patterns is needed. A python-based spray deposition pattern analysis tool, SprayDAT, was developed to estimate spray quality utilizing a cost-effective continuous sampling technique involving digital soand spectrophotometric analysis of blue colorant stains on white Kraft paper. This technique cost 0.2 cents per USD spent on traditional water-sensitive paper (WSP) allowing for continuous sampling necessary for the highly variable deposition patterns delivered by an ASD. SprayDAT conserved droplet densities and more accurately detected stain objects compared to a commonly utilized software, DepositScan, which overestimated stain sizes. However, droplet density exhibited an upper asymptote at 22% stain cover when relating volume median diameter (VMD) due to increasing overlap of stain objects. Spread factor of blue colorant stains was fit to a 2-parameter power equation when compared across six discrete droplet sizes between 112 and 315 µm when droplets were captured in a biphasic solution of polydimethylsiloxane of 100 cSt over 12,500 cSt viscosities. Cumulative digitally assessed stain objects underestimated application volume 270% when compared to the predicted output based on flow rate, coverage, and speed. SprayDAT incorporates a standard curve based on colorant extraction and spectrophotometric analysis to correct this error such that total stain area accurately estimates application volume to within 9%. This relationship between extracted colorant and total stain area, however, is dependent on droplet size spectra. SprayDAT allows users to customize standard curves to address this issue. Using these analysis techniques, continuous sampling of a 29.3-m transect perpendicular to an ASD or ground sprayer spray swath resolved that increasing ASD operational height increases drift and effective swath width while effective application rate, total deposition, and smooth crabgrass control by quinclorac herbicide decreases. Deposition under the ASD was heterogeneous as the coefficient of variation (CV) within the targeted swath exceeded 30% regardless of operational height. At higher operational heights, relative uniformity of spray pattern was improved but droplet density at 11.7 m away from the intended swath edge was up to four times greater and total spray deposited was up to 60% reduced at the highest heights. For each 1-m increase in ASD operational height, 6% of the deposited spray solution, 11% of the effective application rate within the targeted swath, and 7% of smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] population reduction declined. Subsequent studies suggested that total deposition loss with increasing operational height of ASD were likely due to droplet evaporation. Discrete-sized droplets subjected to a 5-m fall in a windless environment exhibited a sigmoidal relationship where 98% volume of 135-µm droplets and approximately 67% volume of 177 – 283 µm diameter droplets evaporated. Addition of drift reduction agents (DRAs) or choosing different nozzle types altered the initial droplet density generated by a flat-fan nozzle. Regardless of DRA additions or nozzle replacement, the distance required to lose 50% of small droplets (< 150 µm diameter) was 6.6 m. Air induction nozzles and DRA admixtures also conserved smooth crabgrass control across 2- and 6-m operational heights, where control was reduced at the 6-m height with a flat fan nozzle without DRA. Spray deposition pattern analysis for multipass ASD and ground applications was conducted by utilizing nighttime UV-fluorescence aerial photography and weed infestation counts in a digitally overlaid grid. Results show that under-application across all devices was consistent and averaged 12%, whereas at least 14% more over-application on the targeted area was observed for ASD, regardless of equipped nozzle types, compared to a ride-on sprayer. Drift also occurred at least 3 times more for ASD application than for a ride-on sprayer and a spray gun sprayer. Using smooth crabgrass infestation annotated from aerial images could not consistently resolve the spatial variability evident in UV-fluorescent imagery presumably due to the innate variability in weed populations. Analysis using SprayDAT revealed insights into factors affecting ASD spray deposition, such as operational height impacting drift, effective swath width, and herbicide efficacy, highlighting the tool's utility in optimizing aerial herbicide applications in turfgrass management. Data suggest that the lowest ASD operational height should be employed to partially mitigate drift and droplet evaporation while improving weed control. Lower operational heights, however, reduce effective swath width and increase heterogeneity of the deposition pattern. Future research should evaluate possible engineering controls for these problems. / Doctor of Philosophy / In recent years, there has been growing interest in using agricultural spray drones (ASD) for applying herbicides in managed turfgrass systems. Traditionally, aerial spraying has not been widely used in these settings, but ASDs are gaining attention. However, there is still a need for a better understanding of how different factors affect spray patterns of ASDs and weed control effectiveness. To address this, novel image analysis software, SprayDAT was developed. It uses white Kraft paper and blue colorant to analyze spray patterns. Compared to traditional methods, SprayDAT provides a cost-effective way to study spray deposition over larger areas, which is important for analyzing the irregular patterns produced by ASDs. The tool showed similar accuracy in detecting spray patterns compared to existing software used with water-sensitive papers, but with some improvements in detecting fine details. SprayDAT was used to analyze spray patterns from ASDs equipped with different nozzles at various heights, as well as ground application methods. It was found that regardless of height, ASDs showed some inconsistency in spray deposition, with about 6% of the spray solution and 11% of the effective application rate being lost for each 1-m increase in ASD height. This loss is likely due to droplet evaporation based on additional laboratory and field studies that directly measured droplet volume loss or stains of small droplets on white paper. In another part of the study, UV-fluorescent nighttime aerial images and weed infestation following herbicide sprays were used to assess spray deposition of multipass ASD applications. It was found that ASDs tended to over-apply in more of the targeted area than ground-based methods and caused more drift of spray to non-target areas. These studies suggest that lower operational heights, such as 2-m above ground, is recommended when controlling weeds with an ASD as effective application rate and weed control will be improved. These low heights, however, increase variability of rate across the intended spray swath and reduce the effective swath width.

Copper chlorophyllin (CuChl) is an antioxidant from renewable sources, which has shown as a potential active ingredient in agricultural crop sprays. The major objectives of this thesis are to understand the colloidal and interfacial behaviors of CuChl, and to develop strategies for improving its effectiveness in field applications. In this project, the following three areas are examined and analyzed. In practice, CuChl-based formulations are sprayed directly onto a plant’s foliage. As such, there is a need to understand how CuChl interacts with relevant plant surfaces. To this end, quartz crystal microbalance with dissipation (QCM-D) was used to quantify the adsorption of CuChl aqueous solutions onto four model surfaces: polystyrene, cellulose, pullulan, and silica. The results showed that cellulose adsorbed the highest amount of CuChl, followed by polystyrene and pullulan. In addition, the results also showed that the surfactants, SDS or DTAB, could alter the binding of CuChl to cellulose when used in concentrations above the critical micelle concentration. CuChl is composed of water-soluble and dispersed components, therefore it is not intrinsically rainfast, which limits its field application. To immobilize CuChl on leaves, a polymer combination of CMC (carboxymethyl cellulose) and PAE (polyamidoamine-epichlorohydrin) was designed for use as a spray adjuvant. The release behaviors of CuChl from dried spray deposits were investigated using varied polymer compositions and concentrations and compared with those of a water-soluble dye, brilliant sulfaflavine (BSF). The results indicated that a small amount of CuChl was immediately released upon exposure to water whereas BSF’s release behavior was dependent on the square root of time. The unusual behavior of CuChl was attributed to the presence of particles in the solution. These nanoparticles were coated with CMC:PAE complex, with the result of being immobilized on parafilm. Suspoemulsion is the most complex agricultural formulation that is composed of both dispersed particles and emulsion droplets. The objective of this work is to understand the relationship between the solution properties of suspoemulsions and the resulting dried deposits on hydrophobic surfaces. The results showed that the distribution of polychlorinated Cu (II) phthalocyanine (PG7) particles in dried deposits was related to the extent to which PG7 particles were adsorbed on or entrained in oil droplets. The PG7 particles that mainly ended up in the center (dome) area after drying were bound to the oil/water interface in the suspoemulsion, whereas individually dispersed particles ended up in the annulus. / Thesis / Doctor of Philosophy (PhD) / Agricultural formulations have been developed and widely applied to crops in an effort to maximize yields to keep up with the food demands of the world’s ever-growing population. However, there are still many challenges associated with the application of these formulations, such as huge losses due to spray drift, wash-off, and degradation during spraying. These issues can reduce the formulation’s overall efficacy and pose serious risks to the environment and human health. The primary objective of this thesis is to explore the agricultural application of a new environmentally-friendly active ingredient, copper chlorophyllin (CuChl). To this end, this work begins by determining CuChl’s colloidal and adsorption behaviors, with a particular focus on its binding tendencies for relevant plant surfaces. Next, a polymer combination was designed as a spray adjuvant to enhance CuChl’s rainfastness performance and CuChl’s release from dried deposits was characterized. Finally, the distribution of dispersed particles in dried suspoemulsion deposits was determined.