Many specialty crops are susceptible to insects and diseases, and as such are reliant on regular canopy pesticide applications to achieve quality attributes required for salability. The majority of specialty crop producers continue to use antiquated pesticide application technologies for directed canopy spraying such as the radial air blast sprayer that has been associated with chemical wastage and off‐target drift of around 40% and 15% of total applied spray volume, respectively. However, precision sprayers are available that result in remarkable improvements to these parameters. The wide‐scale adoption of precision sprayers by specialty crop producers remains low. Reasons for the continued dominance of old technologies include risk averseness of farmers and regulatory bottlenecks. However, as farm labor becomes more expensive, less available, and consumers and regulations favor sustainably produced products, motivations to improve spray application efficiency are increasing. While there are many opportunities and future directions application technology may take, sensor‐controlled sprayer technology that applies a proportionate amount of spray will likely be the primary technology of precision sprayers going into the future. © 2020 Society of Chemical Industry
To optimize pesticide applications to the canopies of deciduous perennial crops, spray volume should be adjusted throughout the year to match the changes in canopy volume and density. Machine-vision, computer-controlled, variable-rate sprayers are now commercially available and claim to provide adequate coverage with decreased spray volumes compared with constant-rate sprayers. However, there is little research comparing variable- and constant-rate spray applications as crop characteristics change throughout a growing season. This study evaluated spray volume, spray quality (e.g., coverage and deposit density), and off-target spray losses of variable- and constant-rate sprayers across multiple phenophases in an apple (Malus domestica) orchard and a grape (Vitis vinifera) vineyard. The variable-rate sprayer mode applied 67% to 74% less volume in the orchard and 61% to 80% less volume in the vineyard. Spray coverage (percent), measured by water-sensitive cards (WSC), was consistently greater in the constant-rate mode compared with the variable-rate mode, but in many cases, excessive coverage (i.e., over-spray) was recorded. The variable-rate sprayer reduced off-target losses, measured by WSC coverage, up to 40% in the orchard and up to 33% in the vineyard. Spray application deposit densities (droplets per square centimeter) on target canopies were typically greater in variable-rate mode. However, the deposit densities were confounded in over-spray conditions because droplets coalesced on the WSC resulting in artificially low values (i.e., few, very large droplets). Spray efficiencies were most improved early in the growing season, when canopy density was lowest, demonstrating the importance of tailoring spray volume to plant canopy characteristics.
Wine grapes are an important agricultural commodity in the Pacific Northwest where grape powdery mildew (GPM) is one of the main disease problems. The efficacy of different sulfur concentrations and different output volumes from an air blast sprayer retrofitted with the Intelligent Spray System (ISS) were evaluated for the management of GPM. The ISS consists of a LiDAR sensor, Doppler speed sensor, embedded computer, flow controller, and individual pulse-width-modulation solenoid valves at each nozzle. GPM cluster severity ranged from 55% to 75% across all trials in the study when using the ISS at its default spray rate of 62.5 ml m-3 and micronized sulfur at 6 g L-1, which was significantly higher than all other fungicide treatments, but lower than non-treated controls. Similarly, leaf incidence values were highest on non-treated vines, followed by micronized sulfur at 6 g L-1 applied at 62.5 ml m-3 , with all other fungicide treatments being significantly lower in all trials. Using the ISS at the 62.5 ml m-3 rate and a rotation of locally systemic fungicides resulted in the lowest observed GPM leaf incidence, and average cluster severity of 11% in both 2019 and 2020, the lowest cluster severity of all fungicide treatments tested. GPM control using the ISS and micronized sulfur was equivalent to a constant-rate air blast treatment at 6 g L-1 when the spray rate of the ISS was increased to 125ml m-3, or if the concentration of sulfur was increased to 24 g L-1. In those cases, the amount of sulfur applied to vines was at or above the minimum label rate from bloom until the end of the season, or the entire season, respectively. This study has shown that sufficient disease control cannot always be expected when mixing pesticides at the same rate as would be used for a constant-rate sprayer in a variable rate sprayer, especially when using contact fungicides like sulfur . With appropriate adjustments, the variable-rate ISS can be a useful tool to reduce pesticide quantities, water required for mixing, and as a result labor, as fewer trips to refill for a given spray event are required.
Grape powdery mildew (GPM) fungicide programs consist of 5 to 15 applications, depending on region or market, in an attempt to achieve the high fruit quality standards demanded by the market. Understanding how fungicides redistribute and targeting redistributing fungicide to critical crop phenological stages could improve fungicide protection of grape clusters. This study evaluated fungicide redistribution in grapevines from major fungicide groups labeled for GPM control. Translaminar and xylem redistribution was examined by placing fungicide-impregnated filter disks on the adaxial or abaxial leaf surface of detached leaves for 10 min and then incubating for 48 h before inoculating the abaxial surface with conidia. Vapor redistribution used Teflon disks sprayed with fungicides and placed on the abaxial leaf surface of detached leaves 48 h before inoculation. Disease development was rated 10 days later. Translaminar movement through calyptra was tested using flowering potted vines. All fungicides tested redistributed through at least one mechanism. Fungicide timing at critical phenological stages (early, mid, and late bloom) was assessed in small plots of cultivar Pinot noir vines. The application of trifloxystrobin, quinoxyfen, or fluopyram at different bloom stages showed that applications initiated at end of bloom resulted in the lowest berry infection probabilities of 0.073, 0.097, and 0.020, respectively. The results of this study suggest that integrating two carefully timed applications of redistributing fungicides initiated at end of bloom into a fungicide program may be an effective strategy for wine grape growers in western Oregon to produce fruit with low GPM infection.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.