Issue link: https://read.dmtmag.com/i/681909
40 JUNE 2016 GOOD FRUIT GROWER www.goodfruit.com R esearchers at Michigan State University's Clarksville Research Center, in collaboration with Cornell University, have answered many of the questions posed about the via- bility of solid-set canopy delivery systems. The high cost and short residual effects of the cur- rent crop of pesticides are increasing demand for more precise chemical delivery, and SSCDS are intended to meet that demand. Per-acre capital costs of prototype SSCDS are 60 percent higher than conventional air blast sprayers. Yet researchers say the effi ciency and safety gains offered by the new system, as well as its usefulness beyond pest control, provides growers with a number of options to earn returns on their investments. Matthew Grieshop, a Michigan State University associate professor of organic pest management, is one of the researchers on the project. "New generation pest controls are more specifi c and more expensive, which is driving demand for applying pesticides more precisely. "Organophosphates are disappearing from the mar- ketplace," Grieshop said, "And with the pollination con- cerns surrounding the neonicotinoids, the fruit industry is facing the loss of a lot of their go-to products." The basics The system under review consists of a central pump- ing station that pushes spray material down tree rows through tubing running along tree canopies. The spray material is then applied via micro-sprinkler nozzles attached to support wires above trees in trellis systems and fruiting walls. For the Michigan trial, the Clarksville researchers attached two lines of micro sprayers — one at 4.5 feet and another at 8 feet — to the tubing. They fi xed single, hori- zontally oriented micro spray- ers on the upper line and two vertically oriented micro sprayers on the lower line, attached with a T-bracket, and spaced both sprayer sets at 6-foot intervals. The system has four operational stages. First, opera- tors pump spray material through the main line at low pressure. To spray, they close the return line and increase air pressure to apply chemicals. For recovery, operators open the return valve and turn on the air compressor to blow residual material back into the spray holding tank. To clean the system, they close the return valve and run the air compressor to clear the micro sprayers. Comparison trials Three years ago, Good Fruit Grower reported on the first-year results of this research project, which was being conducted in three states: Michigan, Washington and New York. A recent report released new results from Michigan, incorporating fi ndings from New York, for the last three years of study from 2013 to 2015. WSU hasn't worked on the project since 2014. Michigan State University researchers ran fi eld trials to compare SSCDS performance against conventional air blast sprayers. They used three tests to compare cover- age: water-sensitive cards, tartrazine dye deposition and an insect pest bioassay. The team placed water-sensitive cards both face up and face down, at 3-foot, 5-foot and 8-foot levels within the canopy. Then, they sprayed plots using both systems at 80 gallons per acre to compare coverage. Over the three-year duration of the trial, SSCDS sys- tems provided better coverage on cards facing up com- pared to cards facing down and tended to provide more coverage higher in the tree rather than lower in the tree, according to the researchers. In contrast, air blast spray- ers tended to provide better coverage of the undersides of leaves and the lower portions of the trees. They also tested for spray distribution within the canopy. Using a food-grade, tartrazine dye mixed into spray applications, results showed much higher spray deposition on SSCDS-treated leaves compared with air blast-treated leaves. The MSU researchers also evaluated SSCDS's per- formance in providing disease and pest control against that of an air blast sprayer. For pest management, they gauged the presence of codling moth, Oriental fruit moth, plum curculio and obliquebanded leaf roller after treatment; for disease control, they monitored for signs of apple scab. The SSCDS provided comparable apple scab control to that of the air blast treatment. Results were consistent with SSCDS plots providing insect control equivalent to air blast sprayers as well, the researchers said. "We collected field data on all three of those pests and apple scab at MSU and saw no difference between SSCDS and air blast-treated plots," Grieshop said. "Both delivery systems signifi cantly reduced damage compared to the untreated control." Cornell University ento- mologist Art Agnello said he compared the fruit quality of apples treated by air blast sprayers and SSCDS harvested from a New York state experimental orchard block. "The data I sent over to Michigan State University for the grant proposal showed the fruit quality was comparable for both systems," he said. The benefi ts Grieshop said one obvious advantage is that this system does not require the use of a tractor. For apple growers whose orchards lie on heavy clay soils, it means not running heavy equipment through the mud during scab season. "It also means reduced incidence of 'iron blight,' equipment-infl icted tree damage," Grieshop said. While the system still requires a single operator, that operator stands outside the orchard and well away from the application process. And because the system is not complex, it requires far fewer skills to operate than trac- tor-based systems. Grieshop said the application process is very fast, approximately 12 seconds. "We think we have far fewer concerns about spray drift because we are just misting the foliage," he said. That's also a benefi t for those growers whose oper- ations are located near housing developments or com- mercial areas: SSCDS run very quietly, he said. Grieshop has just begun exploring using the rapid applications made possible by SSCDS to re-think the rate and frequency at which pesticides are applied. The basic idea would be to apply a full rate of pesticide followed by frequent, subsequent, low-rate applications targeted at maintaining coverage. "For example, if we consider a pesticide with a sev- en-day reapplication window at 100 percent rate that is typically applied twice, we could make the fi rst applica- tion at 100 percent, followed by three reapplications at 25 percent over the next 14 days," he said. It would save about one-eighth of the active ingre- dient and maintain pesticide residuals at a lower, more consistent level on the fruit. "This also could result in reduced residue at harvest," he said. Going forward When the trials began, three universities — MSU, Cornell and Washington State University — shared the grant to evaluate the system. Last year, the U.S. Department of Agriculture did not fund the project, although MSU found some state money to continue the work and Cornell University continued to collect data. Grieshop has written another grant proposal for 2016 that includes both Michigan State and Washington State universities. • A new way to apply chemicals ONLINE For more information about the SSCDS project, including write-ups about its most recent �indings, visit www.canopydelivery.msu.edu Results look promising for solid-set canopy system delivery. by Dave Weinstock COURTESY MICHIGAN STATE UNIVERSITY 1-inch diameter hose on top line Stop-drip device (top) and micro sprayer (below) 3/4-inch diameter hose on lower line Micro sprayer is perpendicular to ground and parallel to tree row Solid-set canopy delivery system "New generation pest controls are more speci�ic and more expensive, which is driving demand for applying pesticides more precisely." —Matthew Grieshop Michigan State University's Clarksville Research Center is testing a solid-set canopy delivery system designed to apply pesticides more precisely than conventional sprayers.