The spray system fills the entire orchard at the same time with a mist that is applied only briefly.
PHOTO COURTESY ART AGNELLO, CORNELL UNIVERSITY
For Cornell University entomologist Dr. Art Agnello, the grant funding for research to develop and evaluate the Solid Set Canopy Delivery System (SSCD) for spraying orchards is gratifying for it builds on what he discovered 15 years ago.
“We tried it then, and, frankly, it worked very well,” he said.
In 1998, he and co-workers at the Geneva Experiment Station in New York put together a crude irrigation-like system, using emitters attached to metal conduit poles to spray insecticides and fungicides in an orchard without using an airblast sprayer and hauling spray solution up and down the orchard alleys.
At the time, he called it a “fixed spray system,” not using irrigation terminology to describe it.
“We bootstrapped it,” he said. “We didn’t have much funding.”
The initial pest control results looked good, but the system needed serious engineering.
Seven years later, in 2005, Agnello got technical help from Dr. Andrew Landers, who came to Geneva in 2001. He had the engineering expertise Agnello didn’t have, and the two completed another study that again showed good pest control using emitters inserted into overhead lines within the row. They set up a larger system at Fowler Farms, where John and J.D. Fowler were interested in finding a system that would allow them to spray their large orchards, where more than 15 spray rigs were running most of the time, and do it in a narrow window that matches the best timing. They hoped it might also cut their machinery, labor, and fuel expenses.
Agnello and Landers are now part of the new, national project headed by Dr. Matt Grieshop at Michigan State University. And Fowler Farms is again included, where a new fixed spray system has been installed.
While studies will be done on efficacy, Agnello believes the chief challenges to be overcome during the SSCD project are mostly engineering ones.
There are some new ideas being tried in the project that address problems of uneven application from uneven pressure. There are new emitters that distribute the spray droplets more thoroughly. Compressed air is being tested to move spray material out of the lines after spraying is done. Return lines can make it a closed system that recovers unused spray material, pushed through by air. New check valves respond to different levels of pressure, allowing one pressure to be used to fill the lines and clear the excess, and a higher pressure to spray them out.
Specialized spray reservoirs are being tried. Conceivably, larger section of tubing in line above the emitter could be filled during solution delivery, then sprayed out in a separate operation using compressed air. Each reservoir would hold a specific dose for each tree, storing it there during the fill phase and spraying it using compressed air after the container is filled.
Agnello is enthusiastic about the new project. In his report in the New York Farm Quarterly after their 2005 trials, Agnello and Landers wrote that it could be used in many of the newer high-density blocks where airblast sprayers are not the most suitable application method.
“Spraying an entire orchard using a fixed system could have several advantages that would justify initial establishment costs and reduce pesticide-associated risks. Spray drift would be minimized without sacrificing adequate crop protection. Pesticide application could be a much more efficient process, achievable in a fraction of the time of tractor spraying, during shorter windows of acceptable spraying conditions, and at times of the year (such as early season) when ground conditions may make it impractical to drive through the orchard. “
Because it would be easier to apply multiple sprays or respray frequently, it would be more practical to use lower pesticide rates or less toxic alternatives, Agnello said, or to use organically approved materials that have relatively short residual life, such as botanicals, microbials, oils, soaps, and insect growth regulators.
In recent years, growers have been adopting high-density plantings with trellises and wires that create an ideal support system for a fixed-in-place spray system.