Commercializing targeted sprayer systems allows producers to reduce herbicide inputs but risks the possibility of not treating emerging weeds. Currently, targeted applications with the John Deere system allow for five spray sensitivity settings, and no published literature discusses the impact of these settings on detecting and spraying weeds of varying species, sizes, and positions in crops. Research was conducted in AR, IL, IN, MS, and NC in corn, cotton, and soybean to determine how various factors might influence the ability of targeted applications to treat weeds. These data included 21 weed species aggregated to six classes with height, width, and densities, ranging from 25 to 0.25 cm, 25 to 0.25 cm, and 14.3 to 0.04 plants m-2, respectively. Crop and weed density did not influence the likelihood of treating the weeds. As expected, the sensitivity setting alters the ability to treat weeds. Targeted applications (across sensitivity settings, median weed height and width, and density of 2.4 plants m-2) resulted in a treatment success of 99.6% to 84.4%, 99.1% to 68.8%, 98.9% to 62.9%, 99.1% to 70.3%, 98.0% to 48.3%, and 98.5% to 55.8% for Convolvulaceae, decumbent broadleaf weeds, Malvaceae, Poaceae, Amaranthaceae, and yellow nutsedge, respectively. Reducing the sensitivity setting reduced the ability to treat weeds. Size of weeds aided targeted application success, with larger weeds being more readily treated through easier detection. Based on these findings, various conditions could impact the outcome of targeted multi-nozzle applications. Additionally, the analyses highlight some of the parameters to consider when using these technologies.

In plasticulture production, smart spray technology can detect weeds and apply herbicides only where needed in the area between raised, plastic-covered beds (row middle). This technology has the potential to reduce herbicide use and lower input costs. A prototype smart spray system was developed at the Gulf Coast Research and Education Center (GCREC) in Wimauma, FL, that utilizes YOLO-V3 convolutional neural networks to differentiate broadleaf, grass, and nutsedge weeds in row middles. Two sets of field experiments were conducted to determine the efficacy of smart spray technology using a combination of preemergence (PRE) and postemergence (POST) herbicides. All treatments reduced weed density, and targeted applications were as effective as banded treatments. Overall, including a PRE herbicide tended to lower weed density compared to POST applications alone, regardless of application technique. Two banded PRE herbicide applications and two targeted POST applications reduced herbicide use by 52% and 13% compared to banded PRE and POST applications in Experiments 1 and 2, respectively. The reduction from two to one PRE-herbicide applications did not result in an overall herbicide use or cost reduction in Experiment 1, as the decrease in PRE herbicides resulted in increased POST-herbicide usage. In the absence of a banded PRE application, targeted compared to banded POST applications, herbicide usage was reduced by 40 to 67% in Experiment 1 and 79 to 84% in Experiment 2. Smart spray technology is an effective weed management tool for row middles in plasticulture production systems with or without PRE-herbicide applications.

New machine-vision technologies like the John Deere See & Spray™ could provide the opportunity to reduce herbicide use by detecting weeds and target-spraying herbicides simultaneously. Experiments were conducted for 2 yr in Keiser, AR, and Greenville, MS, to compare residual herbicide timings and targeted spray applications versus traditional broadcast herbicide programs in glyphosate/glufosinate/dicamba-resistant soybean. Treatments utilized consistent herbicides and rates with a preemergence (PRE) application followed by an early postemergence (EPOST) dicamba application followed by a mid-postemergence (MPOST) glufosinate application. All treatments included a residual at PRE and excluded or included a residual EPOST and MPOST. Additionally, the herbicide application method was considered, with traditional broadcast applications, broadcasted residual + targeted applications of postemergence herbicides (dual tank), or targeted applications of all herbicides (single tank). Targeted applications provided comparable control to broadcast applications with a ≤1% decrease in efficacy and overall control ≥93% for Palmer amaranth, broadleaf signalgrass, morningglory species, and purslane species. Additionally, targeted sprays slightly reduced soybean injury by at most 5 percentage points across all evaluations, and these effects did not translate to a yield increase at harvest. The relationship between weed area and targeted sprayed area also indicates that nozzle angle can influence potential herbicide savings, with narrower nozzle angles spraying less area. On average, targeted sprays saved a range of 28.4% to 62.4% on postemergence herbicides. On the basis of these results, with specific machine settings, targeted application programs could reduce the amount of herbicide applied while providing weed control comparable to that of traditional broadcast applications.