Advancing Sustainability in Tree Crop Pest Management: Refining Spray Application Rate with a Laser-guided Variable-rate Sprayer in Apple Orchards

Advanced variable-rate spray technology, which applies pesticides based on real-time scanning laser rangefinder measurements of plant presence, size, and density, was developed and retrofitted to existing sprayers. Experiments were conducted to characterize the application of four programmed spray rates (0.03, 0.05, 0.07, or 0.09 L·m−3 of crop geometric volume) when applied to Malus domestica Borkh. ‘Golden Delicious’ apple trees using this crop sensing technology. Water-sensitive cards (WSCs) were used as samplers to quantify spray coverage, deposits, and deposit density in the target and nontarget areas, and an overspray index based on a threshold of greater than 30% coverage was calculated. The application rate ranged from 262 L·ha−1 at the programmed spray rate of 0.03 L·m−3 to 638 L·ha−1 at the rate of 0.09 L·m−3. For a given WSC position, spray coverage and deposits increased as the spray rate increased. WSC positions 1 and 2 were oversprayed at all rates. The effect of spray rate on deposit density varied with WSC positions, with high densities achieved by low spray rates for WSCs closest to the sprayer but by high spray rates for WSCs positioned either deeper within or under the canopy. When coalescing deposits were accounted for, deposit densities met or exceeded the recommended pesticide application thresholds (insecticides 20–30 droplets/cm2; fungicides 50–70 droplets/cm2) at all WSC positions for each spray rate tested. The lowest spray rate reduced off-target loss to the orchard floor by 81% compared with the highest rate, dramatically reducing potential exposure to nontarget organisms, such as foraging pollinators, to come into contact with pesticide residues. Applying the lowest rate of 0.03 L·m−3 met deposit density efficacy levels while reducing spray volume by 83% compared with the orchard standard application of 1540 L·ha−1 and by 87% compared with the 1950 L·ha−1 application rate recommended when using the tree row volume method. Thus, there is potential for growers to refine pesticide application rates to further achieve significant pesticide cost savings. Producers of other woody crops, such as nursery, citrus, and grapes, who use air-assisted sprayers, may be able to achieve similar savings by refining pesticide applications through the use of laser rangefinder-based spray application technology.

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Reducing the Nursery Pesticide Footprint with Laser-guided, Variable-rate Spray Application Technology

HortScience ◽

10.21273/hortsci16157-21 ◽

2021 ◽

pp. 1-13

Author(s):

Lauren Fessler ◽

Amy Fulcher ◽

Liesel Schneider ◽

Wesley C. Wright ◽

Heping Zhu

Keyword(s):

Powdery Mildew ◽

Variable Rate ◽

Spray Application ◽

Pesticide Application ◽

Air Blast ◽

Growing Seasons ◽

Wide Range ◽

Application Characteristics ◽

Deposit Density ◽

Control Disease

Nursery producers are challenged with growing a wide range of species with little to no detectable damage from insects or diseases. Growing plants that meet consumer demand for aesthetics has traditionally meant routine pesticide application using the most time-efficient method possible, an air-blast sprayer, despite its known poor pesticide application efficiency. New variable-rate spray technology allows growers to make more targeted applications and reduce off-target pesticide loss. In this study, a prototype laser-guided variable-rate sprayer was compared with a traditional air-blast sprayer. Pesticide volume, spray application characteristics, and the control of powdery mildew were evaluated over the course of two growing seasons. Spray application characteristics were assessed using water-sensitive cards (WSCs) and DepositScan software. This prototype sprayer reduced pesticide volume by an average of 54% across both years despite being tested against a low rate (<250 L⋅ha−1). In 2016, the conventional sprayer had more than double the deposit density on target WSCs among distal trees than the variable-rate sprayer; however, within proximal trees, there was no difference between the two sprayer types. In 2017, when the trees were larger, within both the distal and proximal trees, the conventional sprayer had greater deposit density on target WSCs than the variable-rate sprayer. In 2016, coverage on target WSCs was nearly 7-fold greater with the conventional treatment than with the variable-rate treatment. In 2017, when trees were larger, there was greater coverage on target WSCs in proximal trees (3.8%) compared with those in distal trees (1.0%) regardless of the sprayer type. This variable-rate spray technology provided acceptable control of powdery mildew severity on individual branches and whole trees and maintained the incidence of powdery mildew to levels comparable to that occurring among trees sprayed with a traditional air-blast sprayer. Therefore, the variable-rate spray technology has the potential to effectively control disease, dramatically reduce the pesticide footprint, and preserve natural resources such as ground and surface water, soil, and beneficial insects found within and around nurseries.

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The sensitivity of economic gains from high-speed planting

Advances in Animal Biosciences ◽

10.1017/s2040470017001169 ◽

2017 ◽

Vol 8 (2) ◽

pp. 662-667

Author(s):

C. R. Dillon ◽

J. Shockley ◽

T. Mark

Keyword(s):

Optimization Model ◽

Technological Progress ◽

High Speed ◽

Operating Cost ◽

Cost Savings ◽

Variable Rate ◽

Net Returns ◽

Variable Rate Application ◽

Technology Changes ◽

Profit Potential

Recent technological progress in high-speed planting (HSP) warrants economic analysis of its potential. A whole farm optimization model of a 1000 ha Kentucky, USA corn and soybean operation finds that operating cost savings (labor, fuel, tractor repairs) and yield increases couple in recovering annual ownership costs of HSP technology. Changes in farm net returns are positive for all 12-row planter scenarios and all double speed cases for the 16-row planter but not for a 50% increase in speed with the 16-row planter. The greatest profit potential occurred when adopting the combination of HSP and variable rate application (VRA), with increased net returns of up to 6.57% compared to conventional speed no VRA for the 12-row planter.

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On-Farm Evaluation of Prescription Map-Based Variable Rate Application of Pesticides in Vineyards

Agronomy ◽

10.3390/agronomy10010102 ◽

2020 ◽

Vol 10 (1) ◽

pp. 102 ◽

Cited By ~ 1

Author(s):

Javier Campos ◽

Montserrat Gallart ◽

Jordi Llop ◽

Paula Ortega ◽

Ramón Salcedo ◽

...

Keyword(s):

Plant Protection ◽

Design Procedure ◽

Plant Protection Products ◽

Application Rate ◽

Variable Rate ◽

Variable Rate Application ◽

Pesticide Distribution ◽

Spray Distribution ◽

Disease Damage ◽

High Degree

Canopy characteristics are crucial for accurately and safely determining the pesticide quantity and volume of water used for spray applications in vineyards. The inevitably high degree of intraplot variability makes it difficult to develop a global solution for the optimal volume application rate. Here, the design procedure of, and the results obtained from, a variable rate application (VRA) sprayer are presented. Prescription maps were generated after detailed canopy characterization, using a multispectral camera embedded on an unmanned aerial vehicle, throughout the entire growing season in Torrelavit (Barcelona) in four vineyard plots of Chardonnay (2.35 ha), Merlot (2.97 ha), and Cabernet Sauvignonn (4.67 ha). The maps were obtained by merging multispectral images with information provided by DOSAVIÑA®, a decision support system, to determine the optimal volume rate. They were then uploaded to the VRA prototype, obtaining actual variable application maps after the application processes were complete. The prototype had an adequate spray distribution quality, with coverage values in the range of 20–40% and exhibited similar results in terms of biological efficacy on powdery mildew compared to conventional (and constant) application volumes. The VRA results demonstrated an accurate and reasonable pesticide distribution, with potential for reduced disease damage even in cases with reduced amounts of plant protection products and water.

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A Constant Pesticide Application Rate Sprayer Model

Transactions of the ASAE ◽

10.13031/2013.36606 ◽

1975 ◽

Vol 18 (3) ◽

pp. 0439-0443 ◽

Cited By ~ 7

Author(s):

C. G. Vidrine ◽

C. E. Goering ◽

C. L. Day ◽

M. R. Gebhardt ◽

D. B. Smith

Keyword(s):

Application Rate ◽

Pesticide Application

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Corrigenda - A portable microcomputer-controlled drip infiltrometer. II. Field measurement of sorptivity, hydraulic conductivity and time to ponding

Soil Research ◽

10.1071/sr9850393c ◽

1985 ◽

Vol 23 (3) ◽

pp. 393

Author(s):

BJ Bridge ◽

PJ Ross

Keyword(s):

Hydraulic Conductivity ◽

Surface Soil ◽

Sandy Loam ◽

Application Rate ◽

Variable Rate ◽

Infiltration Rates ◽

Constant Rate ◽

Long Time ◽

Loam Soil ◽

Dry Soil

The lightweight portable drip infiltrometer described in Part I was used to determine the infiltration characteristics of a sandy loam soil. Sorptivity was determined by varying the application rate to maintain surface ponding and by measuring the time to ponding at a constant application rate. Saturated hydraulic conductivity was equated to the long-time steady-state application rate needed to maintain surface ponding. This rate could be determined to a precision of 0.5 �m s-1 (2 mm h-1) and agreed well with core data from 0.5 to 1.0 m depth in the profile. The results obtained were compared with ponded ring infiltrometer measurements. Sorptivities calculated from the ring infiltrometers were greater than those from the variable rate drip infiltrometer which in turn were greater than those from the constant rate drip infiltrometer. This was attributed to the effect of the macropores under the ponded rings and to confining the depth over which sorptivity was measured under constant application rate to the wetter surface soil. In dry soil, the drip infiltrometer measured low initial infiltration rates caused by poor wetting of the soil, but these were not measured by the ponded ring infiltrometers, which had a 50 mm head. In moist soil, poor wettability did not occur. Five equations for calculating sorptivity from measurements of time to ponding under a constant application rate of 8.3 �m s-1 (30 mm h-1) were used and four of these equations agreed within 20%. This was less than the range of sorptivities arising from uncertainties in determining the time to ponding, and the differences between the equations were attributed to the assumptions used in their derivation. It was concluded that any measurement of sorptivity on this soil was difficult to interpret because of non-uniformity in the upper soil profile.

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The effects of spray application rate and droplet size on applications to control soybean rust

10.13031/2013.25050 ◽

2008 ◽

Author(s):

Scott M Bretthauer ◽

Tristan A Mueller ◽

Richard C Derksen ◽

Heping Zhu ◽

Loren E Bode

Keyword(s):

Droplet Size ◽

Application Rate ◽

Soybean Rust ◽

Spray Application

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Variable-rate Spray Technology Optimizes Pesticide Application by Adjusting for Seasonal Shifts in Deciduous Perennial Crops

HortTechnology ◽

10.21273/horttech04794-21 ◽

2021 ◽

pp. 1-11

Author(s):

Lloyd L. Nackley ◽

Brent Warneke ◽

Lauren Fessler ◽

Jay W. Pscheidt ◽

David Lockwood ◽

...

Keyword(s):

Growing Season ◽

Variable Rate ◽

Pesticide Application ◽

Canopy Density ◽

Perennial Crops ◽

Constant Rate ◽

Canopy Volume ◽

Computer Controlled ◽

Spray Volume ◽

Adequate Coverage

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.

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ELEVATED MICROSPRINKLER BENEFITS CITRUS TREES IN A SEVERE ADVECTIVE FREEZE

HortScience ◽

10.21273/hortsci.25.9.1137a ◽

1990 ◽

Vol 25 (9) ◽

pp. 1137a-1137

Author(s):

Larry R. Parsons ◽

T. Adair Wheaton

Keyword(s):

Application Rate ◽

Water Application ◽

Spray Application ◽

Application Rates ◽

Old Trees ◽

Freeze Protection ◽

Overhead Sprinkler ◽

Citrus Trees

Undertree microsprinkler irrigation has protected 1 or 2 year old trees to a height of 1 meter during severe advective freezes. During the severe December 1989 freeze, microsprinklers elevated to 0.9 meter protected 5 year old citrus trees to a height of 2 meters. Limb breakage due to ice loading was negligible. Protection was achieved with water application rates less than half that required by some overhead sprinkler models. Survival is attributed to 1) continuous spray from the microsprinkler rather than periodic spray from a rotating overhead sprinkler, and 2) effective localized application rate on branches intercepting spray is more than average overall spray application rate. Elevated microsprinklers provide freeze protection to a greater height and allow for more rapid post-freeze recovery.

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Spray application volume test in apple and pear orchards in Catalonia (Spain) and Variable Rate Technology for dose adjustment.

10.13031/2013.20624 ◽

2006 ◽

Author(s):

Alexandre Escolà ◽

Ferran Camp ◽

Francesc Solanelles ◽

Santiago Planas ◽

Felip Gracia ◽

...

Keyword(s):

Dose Adjustment ◽

Variable Rate ◽

Spray Application ◽

Variable Rate Technology ◽

Application Volume

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Precision for Smallholder Farmers: A Small-Scale-Tailored Variable Rate Fertilizer Application Kit

Agriculture ◽

10.3390/agriculture8040048 ◽

2018 ◽

Vol 8 (4) ◽

pp. 48 ◽

Cited By ~ 7

Author(s):

Jelle Van Loon ◽

Alicia Speratti ◽

Louis Gabarra ◽

Bram Govaerts

Keyword(s):

Rural Communities ◽

Precision Agriculture ◽

Smallholder Farmers ◽

Nutrient Status ◽

Fertilizer Application ◽

Application Rate ◽

Small Scale ◽

Variable Rate ◽

User Friendliness ◽

The Right

Precision agriculture technology at the hands of smallholder farmers in the developing world is often deemed far-fetched. Low-resource farmers, however, are the most susceptible to negative changes in the environment. Providing these farmers with the right tools to mitigate adversity and to gain greater control of the production process could unlock their potential and support rural communities to meet the increasing global food demand. In this study, a real-time variable rate fertilizer application system was developed and tested as an add-on kit to conventional farm machinery. In the context of low investment costs for smallholder farmers, high user-friendliness and easy installment were the main concerns for the system to be viable. The system used nitrogen (N)-sensors to assess the plant nutrient status on the spot and subsequently adjust the amount of fertilizer deposited according to the plant’s needs. Test bench trials showed that the add-on kit performed well with basic operations, but more precision is required. Variability between N-sensors and metering systems, combined with power fluctuations, created inaccuracies in the resulting application rate. Nevertheless, this work is a stepping stone towards catalyzing the elaboration of more cutting-edge precision solutions to support small-scale farmers to become successful, high producing agro-entrepreneurs.

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