Issue link: http://read.dmtmag.com/i/155412
growers need to adjust sprayers for deposition and drift P recise application of pesticides in orchards provides growers with better crop protection, less environmental pollution, and better use of resources. It costs less when pesticides are not wasted. Since coming to Cornell University in 1998, Dr. Andrew Landers has been working to make airblast canopy sprayers, designed more than 50 years ago, better fit modern, well-pruned orchards. "Many canopy sprayers use some form of air assistance from fans that are frequently too large for these orchards," Landers said. "The large-diameter fan creates too much air for the target canopy. Air speed and volume need to be adjustable according to the growth stage of the canopy." Much of Landers's work has been aimed at making airblast sprayers do their work better, but he is also involved in a project that, in the future, may eliminate airblast sprayers completely. Called the solid-set canopy spray delivery system, it would use fixed-in-place "irrigation" lines, nozzles, and emitters for application of pesticides, plant growth regulators, and even water for evaporative cooling. Conceivably, such a method would allow precise timing—an all-at-once, short-duration application at greatly reduced rates. The project involves researchers across the country. While this may be a system for the future, growers now need to adjust their airblast sprayers in ways that improve deposition and reduce drift. In an article in Good Fruit Grower earlier this year, Landers said that the work at Cornell has focused on matching airflow to the canopy, and changing airflow as the canopy develops. "Ideally, air volume should match canopy volume," he said. Ideally, that would change tree by tree, and deliver no spray where there is no tree. Sensing systems have been developed that detect canopy density and size so that airflow and liquid application rate can be adjusted in real time. "This allows small trees with sparse leaf growth to have less spray and less air and to increase airflow and liquid spray as the canopy develops," Landers said. Modern airblast sprayers are fitted with a gearbox, but usually the slowest fan speed is only about 20 percent slower than the fastest speed. "Using a hydraulic motor to drive the sprayer fan —Dr. Andrew Landers allows the operator to regulate the air velocity leaving the sprayer," Landers said. "At Cornell University, we retrofitted an axial fan airblast sprayer with a hydraulic motor and a hydraulic control valve, fitted in the tractor cab, to allow the operator to infinitely vary the fan speed from 0 rpm up to 540 rpm. "The operator can reduce air speed during early to midseason applications and increase it for full canopy applications," he said. Landers also developed the "Halsey doughnut," an air restriction device made of two circular wooden plates with intake holes, the size of which can be adjusted simply by turning one plate. This restricts airflow at the fan intake. Cornell researchers also developed and patented an adjustable louvre system, electrically actuated, to adjust airflow from either tower sprayers or traditional airblast sprayers. —R. Lehnert photo courtesy of cornell university "Ideally, air volume should match canopy volume." Andrew Landers discusses air flow direction during a grower workshop. He helped develop a sprayer that could sense canopy density and adjust rate to match each tree. "The system tracks development of key insect pests and diseases using degree-day and infection-risk models. "The models indicate pest status, pest management advice, and sampling options, and are linked to an interactive system that helps growers choose appropriate materials when pesticide use is recommended." The whole Internet experience is further broadened by hyperlinks that take growers to other online resources—color photos of bud development stages, fact sheets on the pests, sampling charts, ratings of the efficacy of various insecticides, remarks about effects on beneficial s pecies, and reentry and preharvest intervals. And it's all in one place. Weather Service data National system? The Cornell system is being developed in several other eastern states as well. In New York, it's called NEWA—short for the New York State Integrated Pest Management Network for Environmental and Weather Applications. Insect pest development stages are calculated from degree-day accumulations, using data from National Weather Service airport weather stations across the state. So growers now fire up their computers and their Web browsers before firing up the tractor and filling the sprayer. Insects addressed on the Web site are the apple maggot, oriental fruit moth, codling moth, plum curculio, obliquebanded leafroller, and spotted tentiform leafminer. Disease predictions are available for apple scab and fireblight. A summer disease development model for sooty blotch and flyspeck was to be available this summer. Growers access the apple insect models through the pest forecasts link on the NEWA home page (http://newa.cornell.edu). They select a nearby weather station and a pest of interest, which takes them to a page that tells them what phenological stage the trees are at, what the pest is doing at that stage, and recommends action if needed. When spraying is recommended, available materials are reviewed and a decision filter helps the grower pick the appropriate material. Growers can adjust the phenological stage to match what they observe happening in their orchards. More growers are putting in their own weather stations, connected to their own computers with line-ofsight wireless systems or cell phones. In 2011, Cornell received a Specialty Crops Research Initiative planning grant to explore making the Cornell model the basis of a national system. Specialists from the University of Massachusetts, Virginia Polytechnic Institute and State University, Michigan State University, Pennsylvania State University, Oregon State University, North Carolina State University, Iowa State University, and the Northeast Regional Climate Center worked together and prepared a full SCRI proposal in 2012. It was not funded, but they plan to resubmit it, Agnello told growers during the Summit. "We plan to reconfigure the platform based on the current New York Web site," he said. Using this basic structure, sites anywhere in the United States could input local weather data. Each area could be customized by local researchers, extension personnel, and industry stakeholders to include local insect and disease problems and forecasting capabilities, crop growth information, and management options and recommendations. In addition, as a national system, it would help apple growers outside of major production areas have access to the latest information, and it would help all growers know about and use the latest ideas in integrated pest management. "We intend to have the potential to augment this site with additional capabilities, such as thinning models, harvest windows, and postharvest storage disorders," Agnello said. www.goodfruit.com • Good Fruit Grower SEPTEMBER 2013 11