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Do-It-Yourself "Post-Directed" Sprayer
Over the years, use of post-directed nonselective herbicides has been a mainstay for some producers, particularly in no-till.
"If you can get herbicides like Atrazine or Gramoxone below the crop canopy, they'll do a great job of cleaning up low-growing weeds," says Carl Hovermale, a Mississippi State University research agronomist at the South Mississippi Branch Experiment Station near Poplarville.
There have been a number of sprayers on the market designed to get herbicide below the crop canopy. Hovermale says most are rather cumbersome and can be difficult to adjust and calibrate.
So he recently went back into his archives to pull out plans for a sprayer that he and Herb Willcut, then a Mississippi State University extension agricultural engineer, made for post-directed applications nearly two decades ago. "It's simple to build and not at all expensive," he says.
It's built on a tractor-mounted toolbar made of 2 3/8 in. square steel tubing. A series of legs drop down between each row middle. They're made of 1-in. square steel tubing, cut about 54 in. long. Each leg is fastened with a bolt onto a bracket welded to a 3 or 4 in. section of 3 in. square tubing, which is just the right size to slide onto the toolbar. The mounting bolt acts like a hinge, allowing the leg to float up and down. A setscrew in the mounting tube allows it to be adjusted to row width.
The legs angle down from the toolbar at a 45 degree angle, with another 45-degree bend at the lower end that forms a shoe. The shoe is reinforced with a steel plate so it won't wear out as it slides through the field.
A flood or wide angle flat fan spray nozzle mounts on each of the legs using a collar made from a 4 in. section of square tubing that slides the leg. The nozzle-mounting bracket is made so it can flex in an arc, making it easy to change the angle of the nozzle.
"My field workers liked this sprayer a lot because it is so simple to set up," says Hovermale.
About the only problem with the sprayer was the legs tended to bounce at higher speeds in uneven no-till soil conditions. A recent version of the sprayer, built by Brian Freed, a Lexington, Illinois, crop consultant, uses a heavier metal strap for the sliding shoe to solve the bouncing problem. Except for using heavier materials, Freed's post-direct sprayer is nearly identical to the one Hovermale and Willcut designed in the early 1980's. Another way of solving the bounce problem would be individual springs on the legs. "One of my clients removed the shanks and sweeps from a cultivator and put height-adjustable nozzles on the parallel linkage. It does a really good job," Freed says.
Plans for the simple no-till post direct sprayer are available from the Mississippi Cooperative Extension Service.
Contact: FARM SHOW Followup, Carl Hovermale, research agronomist, South Mississippi Branch Experiment Station, Mississippi State University, P.O. Box 193, Poplarville, MS 39470 (ph 601 795-4525; fax 601 795-0653; email: ca1@ra.msstate. edu).

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2001 - Volume #25, Issue #3