Northeastern IPM Center Partnership Grants Projects Funded, 2006

*Award shown is total amount to be used over the course of the project term.

Project Summary

Northeastern US apple growers apply a number of pesticide sprays to their trees annually. Traditionally they use airblast sprayers, which creates a plume of spray, a variable proportion of which hits the target. The result is often poor distribution within the canopy, leading to ineffective pest control plus off-target drift, leading to environmental pollution and economic inefficiency. Modern orchards comprise numerous planting densities and tree canopies, ranging from dwarf trees on narrow row spacings to large trees in wide rows. Spray application in large scale, high density plantings requires many hours of travel, along miles of tree rows, creating high labor and machinery costs, and affecting the timeliness of application. In such high density plantings, it is possible to construct a fixed arrangement of spray nozzles capable of contacting all portions of the trees with a spray that is maintained for just long enough to completely cover all canopy surfaces. By eliminating the need to contact the target with a uniform spray source travelling past it, some of the intrinsic inefficiencies and drift hazards of contemporary airblast spraying might be overcome. This project will result in the optimization of a fixed spraying system being developed in a high density apple planting on a commercial farm in Wolcott, NY. Preliminary trials have demonstrated the ability to apply a spray solution to the trees using this system. Further work will focus on refining its spray deposition and delivery characteristics, and use of direct pesticide injection to more safely and efficiently handle the pesticides. Also, the economics of using this system and its reliability over time, and its biological effectiveness in controlling insect and disease pests on a seasonal basis will be assessed.

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Objectives

1. Refine and optimize the engineering elements of a pesticide application system of tubing and nozzles fixed into the canopy of high-density apple trees.

2. Determine the physical aspects of spray deposition and distribution patterns in the tree canopy achieved, as well as pesticide drift and off-target deposition, using a fixed spray system, compared with a conventional airblast sprayer.

3. Evaluate pest control efficacy and economics of use with each type of application method.

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Problem, Background, and Justification

The application of pesticides to fruit throughout the Northeastern US, as in the rest of the world, gives rise to concern, primarily due to inaccurate application, which often results in high residues and environmental pollution. Inaccuracy, due to over/under application, may result in high levels of disease or insect activity. Air and water pollution is a major concern due to pesticide drift. There is also a growing concern for food safety and accountability among consumers who purchase fruit.

Apple systems in New York, Pennsylvania and Massachusetts
Apple production in the eastern United States is a high value crop, approaching an annual farm-gate value of $450 million with production on 6,582 farms. According to NASS (2004) in 2002, the area planted to apples in NY was 45,000 acres, in PA 28,110 acres and in MA 4,479 acres. Projected yields for the 2005 season in NY: 1,060 mil lbs, Pa: 420 and MA: 35 mil lbs.

Grower priorities: Fruit spraying for insect and disease management
Surveys of fruit growers of New York (NY IPM 2004), based upon stakeholder input, show that evaluation of sprayers, sprayer management and fruit coverage issues are a research priority in tree fruits and apples in particular. Diseases such as apple scab in tree fruit are top priorities, along with arthropod pests such as obliquebanded leafroller and mites. Priorities developed by members of the Northeastern IPM Fruit Working Group include sprayer and pesticide application resources (evaluations, calibration, best use patterns, etc.). They also list evaluation of sprayers and coverage issues, plus spray drift onto neighbors as priorities for research with all tree fruit (Northeastern Pest Management Center 2004). Apple scab and OBLR management, including timing and coverage, are specific priorities.

Similarly, the New England Apple pest management strategic plan 2003 states a priority research area is to continue to evaluate spray application strategies designed to reduce pesticide use with insecticides (Northeastern Pest Management Center 2004). Also included as research priorities are OBLR and mites in apples along with apple scab control.

Who would benefit from this work
A primary beneficiary of this work would be the community of NY apple producers who are continually searching for improved methods of applying pesticides efficiently without sacrificing control efficacy. While the system described in this proposal would not be intended for all planting systems, it could be used in many of the newer high-density blocks where airblast sprayers are not the most suitable or required application method. Because drift and off-target deposition would be reduced with this method, adjacent properties and their occupants would secondarily benefit from lowered risk.

Fowler Bros. orchards, Wolcott, NY, where this work is being conducted, is the largest tree fruit producer in the state, with an operation comprising some 2,000 acres of orchards producing 21 varieties of apples for distribution nationwide and overseas. A growing proportion of their acreage is being converted to high density plantings such as the "super-spindle" training style where the fixed spray system is being developed. Co-owner John Fowler has expressed a high interest in this approach to pesticide application because of the improvement it may offer in spray efficiency and effectiveness compared with traditional tractor-drawn airblast methods, which he finds onerous, as well as the potential ability to greatly reduce off-target pesticide drift.

Previous and ongoing work
Direct injection sprayers have been developed by many researchers for boom sprayers in conventional field crops, but only one paper, Tennes et al. (1976) has been published in their application to fruit crops where they used four direct injection pumps inside a trailed tunnel sprayer. Direct injection sprayers offer the operator many advantages, including reduced environmental pollution and operator contamination (Landers 1992, 1997). Injection sprayers eliminate tank rinsing and allow rapid changes in dose rate. The main tank of the sprayer holds clean water only. Pesticide is injected into the water flow via a piston or a peristaltic pump and the resultant mix flows through the pipes to the nozzles. A manual or electronic controller adjusts the pesticide injection pump according to changes in operating requirements, e.g., changes in application rate and pesticide required.

A fixed spraying system was devised at NYS Agric. Expt. Station, Geneva, and preliminary trials were conducted to measure its efficiency at applying pesticides and controlling insects and diseases. Spraylines were fixed to metal conduit poles at three different heights and fitted with Netafim DAN 7000 sprinkler nozzles. Preliminary trials were conducted in two blocks each of Red Delicious and Empire apples on M.9 dwarfing stock located in a research orchard at this experiment station (Agnello et al. 1999). Tracer solution, using micronutrients, was used to monitor spray deposition and a conventional airblast sprayer was connected, via a hose, to the spraylines passing through the trees. The fixed line system orchard blocks were compared with blocks treated with a conventional airblast sprayer. The scope of the preliminary trials was small, but results over two years showed control of diseases and insect pests such as plum curculio was equal to that obtained with a conventional airblast sprayer.

In 2005, a pesticide application system was devised, similar to a fixed irrigation system, in a larger scale, 0.9-acre block of dwarf super-spindle Gala apple trees in a cooperating grower’s orchard in Wolcott, NY. Two 3/4-inch plastic pipes (laterals) were positioned through the canopy of the apple trees, following the top support wire at 8 feet and the bottom wire at 3.5 feet above the ground. Small emitters, Netafim DAN 7000 series, with an 8 mm orifice and flat pattern spreader (Netafim, Fresno, CA) were installed at 6-foot intervals along the length of the pipe. A 2-inch main pipe was run along the junction of the rows to a central filling position. Pipe diameters were calculated based upon a hydraulic analysis computer program devised by W. Shayya for irrigation purposes.

A trailed application unit was constructed using a 300 gal water tank and a gasoline-driven centrifugal pump producing a flow of 90 gallons/minute at 36 psi. Two DOSMATIC A80-2.5% proportional injection pumps (Dosmatic USA, Carrollton, TX) were fitted into the water flow line after the pump. The water-driven pumps were fitted with super corrosive transfer (SCT) kits to avoid damage to the pump seals from solvents in the pesticides. The pumps dispense pesticide at a known rate into the water stream in the spray pipeline, the injection rate being adjustable from 0.2–2.5% or 1:500 to 1:40. The resultant mix was then pumped along the main pipe to the laterals within the tree canopy. This arrangement was used to apply the grower's standard mixture of insecticides and fungicides in July-Aug 2005, for the final three crop protectant sprays of the season. Although the system was functional, a number of engineering challenges and anomalies were encountered that need to be addressed to optimize and improve system performance in order to facilitate grower acceptance and implementation on a commercial scale.

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Evaluation Plans

Development of the current fixed spray system into a workable, efficient apparatus, the focus of Objective 1, will be a sequential, intuitively motivated endeavor comprising a number of discrete modifications and gradual improvements that should ultimately result in a design and operational profile that we can objectively characterize as optimal for the purposes of the trial being conducted. The engineering progress attending each operational element under review should be self-evident within the context of the system tests we undertake in our efforts to reach this optimal design; our success will be determined by our ability to end up with a mechanically sound method for applying pesticides easily and reliably with this equipment.

The measurements of spray deposition and distribution (Objective 2) will result in quantifiable readings of the percent coverage of numerous, specifically located targets. Aggregate comparisons of thoroughness of coverage in key canopy locations will inform our evaluation of the suitability of this spray application method relative to a conventional airblast sprayer. Similarly, patterns of spray distribution and presence as measured by target strips placed at various distances from the sprayed trees will indicate the extent to which this method reduces the incidence of off-target spray exposure in a realistic agricultural use setting.

Evaluation of pest management efficacy using this approach will be possible primarily by comparing pest populations in-season and fruit quality (damage) levels at harvest with those obtained from the airblast-treated half of the orchard. An economic comparison between these methods will be somewhat speculative, based on the preliminary stage of development of this system, but should be possible at a reasonable enough level to indicate potential applicability of a fixed spray method on a larger commercial scale. Of particular interest will be the willingness of the grower cooperator to consider using this method on an expanded area of his farm.

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