Submitted to: Transactions of the ASABE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2008
Publication Date: 12/5/2008
Publication URL: hdl.handle.net/10113/26985
Citation: Zhu, H., Derksen, R.C., Ozkan, H.E., Reding, M.E., Krause, C.R. 2008. Development of a Canopy Opener to Improve Spray Deposition and Coverage Inside Soybean Canopies -- Part 2: Opener Design with Field Experiments. Transactions of the ASABE. 51(6):1913-1921. Interpretive Summary: Soybean rust has been found in the United States during the past few years. It can cause a great soybean yield loss if fungicides are not applied to the lower part of canopies with proper spray equipment at the right time. Penetration of spray droplets into the lower parts of the soybean canopy using a conventional boom sprayer is rather difficult, especially under dense canopy conditions. An experimental mechanical canopy opener was developed with the assistance of mathematical models and attached to a conventional boom sprayer to increase spray deposition and coverage inside soybean canopies. Field experiments were conducted to evaluate the effectiveness of a canopy opener in comparison with a conventional boom sprayer, and an air-assisted sprayer. Spray deposition and coverage inside canopies were greatly improved by attaching the mechanical canopy opener to the conventional sprayers with relatively shorter booms. The opener was simple and inexpensive in design and growers themselves could build and integrate it into their own sprayers.
Technical Abstract: Conventional boom sprayers usually are not effective in delivering droplets to inner parts of dense target canopies, such as soybeans at the growth stage from R3 to R5. An experimental mechanical canopy opener was developed with the assistance of a mathematical model and attached to a conventional boom sprayer to increase spray deposition and coverage inside soybean canopies. The opener consisted of a 25 cm diameter metal pipe to push canopies forward, and a frame for connecting the pipe to the spray boom. Field experiments were conducted to determine the amount of spray deposition and percentage of spray coverage on artificial targets at the middle and bottom of soybean canopies with three opener depths (7.5, 15, 22.5 cm), three opener widths (15, 25, 35 cm), and two different sizes of flat fan nozzles. Additional field experiments were accomplished to compare spray deposition and coverage inside soybean canopies among treatments using an air-assisted sprayer, the conventional boom sprayer with the opener, and the boom sprayer with a conventional flat-fan nozzle and a dual-pattern nozzle assembly without the opener. At the time of experiments, the soybean plants were at R5 growth stage with an average height of 1.06 m. The opener with a depth of 25 cm or larger significantly increased the spray deposition and coverage inside canopies while the opener depth from 7.5 to 22.5 cm had little influence on the spray deposition and coverage. The boom sprayer with the opener produced no significant difference in spray deposition and coverage at the middle of canopies from the air-assisted sprayer, but it did produce significantly lower spray deposition and coverage at the bottom of canopies than the air-assisted sprayer. With assistance from the opener to push the top of canopies, spray deposition and coverage on targets inside soybean canopies by the boom sprayer was improved.