The study was conducted at the University of Nebraska Pesticide Application and Technology Laboratory in North Platte, Nebraska in July 2015. Two application volume rates (100 and 200 l · ha−1) and three nozzle types (XR, AIXR, TTI) were selected at two flow rates (0.8 and 1.6 l · min−1) and at a single application speed of 7.7 km · h−1. Each collector type [Mylar washed (MW), Mylar image analysis (MIA), water-sensitive paper (WSP), and Kromekote (KK)] was arranged in a randomized complete block design. Each nozzle treatment was replicated twice, providing six cards of each collector type for each nozzle treatment. A water + 0.4% v/v Rhodamine WT spray solution was applied, given the fluorescent and visible qualities of Rhodamine, which allows it to be applied over all the collector types. MW had the highest coverage at 18.3% across nozzle type, followed by WSP at 18%, KK at 12% and lastly by MIA at 4%. MW resulted in a 58% increase in coverage, WSP in a 56% increase, and KK only an increase of 39% when the volume rate was doubled from 100 l · ha−1 to 200 l · ha−1 across nozzle type. MW coverage was similar to KK for half of the nozzles (XR 11002, XR 11004, AIXR 11002). Droplet number density fixed effects were all significant for nozzle type and collector type (p < 0.001) as was the interaction of nozzle type and collector type (p < 0.001). Results from this study suggest a strong correlation to data produced with WSP and MW collectors, as there was full agreement between both types except for the TTI 11004. Using both collector types in the same study would allow for a visual understanding of the distribution of the spray, while also giving an idea of the concentration of that distribution.

Nozzle type and herbicide application timing can affect herbicide efficacy. Prickly sida ( Sida spinosa) and barnyardgrass ( Echinochloa crus-galli) are problematic weeds in eastern Mississippi cotton production and have reduced yield in recent years. Field studies were conducted at two locations – Brooksville, MS (2018, 2019) and Starkville, MS (2019) to understand the nozzle type and herbicide application timing effects on prickly sida and barnyardgrass control in cotton. Studies also compared applications made by an eight-nozzle tractor-mounted sprayer with a four-nozzle backpack sprayer. Herbicide applications were made at four timings: preemergence (PRE), early-postemergence (EPOST), mid-postemergence (MPOST), and late-postemergence (LPOST) corresponding to the preemergence (immediately after planting), two-to-three leaf, four-to-six leaf, and early-bloom stages, respectively. Treatments were made at 140 l · ha−1 applied at each growth stage, with nozzle type and sprayer as variables by each timing. Results showed no differences in treatments applied with backpack and tractor-mounted sprayers. Control of barnyardgrass was significantly affected by nozzle type, but control of prickly sida was not significantly influenced by nozzle type. In all three site-years, plots receiving a MPOST only herbicide application resulted in less weed control than areas receiving a two-pass POST herbicide program. Cotton yield was significantly affected by the herbicide program at one site-year, but was not significantly affected by the herbicide program except where cotton injury exceeded 15%. A two- or three-pass herbicide program was most effective in controlling prickly sida and barnyardgrass in Mississippi cotton.