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In use for more than half a century, the airblast sprayer may go the way of the dodo bird, he suggests. In field days in Washington and Michigan, the researchers showed just how much they were able to do in one year. Horticulturists, entomologists, pathologists, engi- neers, and economists established replicated trials at Washington State University's research orchards in Wenatchee (apples) and Prosser (cherries), at Cornell University and at Fowler Farms in New York, and at sev- eral sites in Michigan, including orchards at the Clarksville Horticultural Experiment Station, at the East Lansing research orchard, and at the Belding farm of Ed and Mike Wittenbach. John Nye with Trickl-eez Irrigation in Michigan is involved in designing the systems and in testing them in the commercial orchards in Michigan and New York. Dr. Jay Brunner, director of WSU's Tree Fruit Research and Extension Center in Wenatchee, said trials were con- ducted in Washington this summer to compare codling moth and mildew control in blocks where the pesticide was delivered through the solid set system versus by an airblast sprayer. Trials in the eastern United States are looking at how the different spray application systems affect control of fireblight and scab. The systems vary in design and type and density of emitters. During a summer field day at WSU's Sunrise research orchard, Brunner explained that the tubing the emitters are attached to forms a big loop. Once the loop is filled with solution, the pressure is raised using an air compres- sor, and the emitters all come on at the same time, deliv- ering 100 gallons per acre of solution in 13 seconds. After the spray is applied, the solution in the system is recap- tured, and the system is cleaned out with air. Different types and orientations of emitters are being evaluated. John Nye at Trickl-eez Irrigation, whose engineering expertise makes him part of the study, suggested this double microsprinkler— two fitted back-to-back and oriented so that the plane of the spray shadows are vertical rather than horizontal—would produce a spray pattern that would better reach the lower canopy areas and hopefully help to wet the undersides of the foliage. In Michigan, experiments were set up in apples and sweet cherries, with the sweet cherries being grown in high tunnels. A few years ago, MSU horticulturist Dr. Greg Lang began work with the fixed-in-place spray system for sweet cherries in tunnels. Two years ago, MSU entomologist Dr. Larry Gut began looking at delivering pheromones for mating disruption through a similar system. Dr. Jim Flore said that disasters like the one that struck Michigan's fruit crops this year because of very warm weather in March followed by April freezes may be preventable in the future. Research has shown that bud development can be set back two to four weeks by using evaporative cooling when temperatures rise above 50°F, he said. Ines Hanrahan, with the Washington Tree Fruit Research Commission, will compare standard overhead cooling systems with the solid-set system for sunburn control. Typically, an overhead cooling system applies water for a 15-minute period when the temperature reaches a threshold. The solid-set system would apply water for only 35 seconds at a time but more frequently so the total amount applied would be the same, Brunner said. Flore also envisions using the system to apply calcium sprays to prevent sweet cherries from cracking and to apply growth regulators such as ethephon. Dr. Mark Whalon notes that, when moisture is ade- quate in the soil, nematodes can be used to eliminate plum curculio larvae pupating in the soil. Could this sys- tem provide that moisture? Phil Schwallier, who works with chemical thinning of fruit and use of Apogee to shorten apple terminal growth, said, "This system should be used for everything. It should totally replace the airblast sprayer." MSU horticulturist Dr. Ron Perry was called on to work with engineers to develop the system itself. He was in charge of the installations at Clarksville. MSU entomologist Dr. John Wise is studying deposi- tion patterns. He wants to see how the application system affects the amount of spray deposited on the orchard floor and on the upper and lower surfaces of the leaves and how different kinds and placements of emitters affects coverage. In New York, reservoir systems are being studied. Instead of filling the lines with spray material, reservoirs above each emitter could be filled with the exact amount of spray material needed to fill its space. Less material would be needed to fill the lines—a serious considera- tion. Perry said it takes 150 gallons of material to fill the lines in the two-acre test orchard at Clarksville, and 12 to 20 seconds to apply about 70 gallons per acre. There was long discussion at the field day at the Clarksville station about how different materials require different levels of coverage on foliage and how the system would have to be operated differently to apply them. Brunner said there are other issues to explore in the long term. For example, if an acre of orchard can be treated in a couple of minutes, can pesticides be applied at lower rates but more frequently? "We're thinking we can move more and more towards a low-residue approach, but that's yet to be determined," he said. "That's not the objective of the current project." Grieshop and Wise both noted that wind affects air- blast sprayers and the fixed system differently. A slight wind might help move the spray through the canopy when it's applied by a solid-set system, Grieshop said. Air- blast sprayers overcome the effect of wind by supplying abundant wind of their own. Economists are also part of the project. The cost of installing such a system could be high but offset by sav- ings in equipment, labor, and time—and the loss of fruit quality that can come from lack of application timeliness. • 22 NOVEMBER 2012 GOOD FRUIT GROWER www.goodfruit.com PHOTO COURTESY ART AGNELLO, CORNELL UNivERSiTY