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Spraying it smart

A thorough review of your spray rig and application methods can save money and improve results.

Dick McPherson likes the way his 600-gal. pull-behind sprayer works. Its 40-ft. boom easily follows the irregular contours of his corn and soybean fields, allowing him to reach tough weeds in tight corners that a larger system might miss. Still, the Indianola, IA, farmer believes that, after five years of service, the system could benefit from some updates.

"New spray monitor controls would be helpful," says McPherson, who farms with his brother Bob and applies herbicides on more than 1,700 acres of corn and soybeans annually.

This year, more Iowa farmers will be out in their fields at spring application time. Iowa State extension specialists estimate that farmer applications will increase 10% this year, fueled by the need to cut costs and the use of simpler weed-control programs. A similar trend is unfolding across the country.

Extension specialists say you can realize $5/acre in out-of-pocket, near-term savings by making your own applications. But that prize requires a price: Your spray equipment and application technique must be capable of providing effective and efficient results.

Update equipment An old sprayer can do the job of a new one, if it's in good condition. Making a few updates is usually a sound investment, says Mark Hanna, agricultural engineer for Iowa State University. He says financial institutions are receptive to making loans for sprayer improvements, because the return on investment is easy to determine. The following are Hanna's recommendations. You could implement them all for about $2,500.

Electric shutoff controls. These allow you to shut off different sections of the boom, an especially valuable feature for spraying end rows or in herbicide-sensitive areas. Depending on boom length, you may need controls installed for the left, center and right sections. Retail cost: approximately $300 to $500.

Diaphragm check valves. These help prevent any dribbling from the nozzles when you shut off the spray stream. Retail cost: approximately $200.

Boom suspension system. Any bouncing in the field impacts the spray pattern and coverage. For about $1,500 you can alleviate most of the equipment problem, though you still must maintain proper speed and pressure.

Clean water tank. This feature can help minimize potential contamination problems. Increasingly farmers use a tank to mix and load in the field, and then for cleanup purposes. Retail cost: approximately $300.

If you own an older sprayer, you may want to invest in a new stainless steel tank. Traditional fiberglass tanks present some concerns. "Pores in fiberglass can trap and hold product molecules, which can then interfere with other products you mix later on," explains Bob Wolf, extension specialist, application technology, Kansas State University.

As you shop for a new tank, always evaluate the mixing apparatus. An agitation system that goes across the bottom of the tank performs the best mixing job, as opposed to one that is only in the center or in one corner. This holds particularly true with dry flowable products, which require strong agitation for thorough mixing. Once you start the spraying process, don't stop until you empty the tank. If youmust take a short break, leave the spray system running so that no settling occurs and no misapplication results.

If your spray system is antiquated, you may need to replace it outright or consider leasing. One company, RHS of Hiawatha, KS, offers such an option, based on a five-year lease with 5.9% simple interest. This is the second year it has offered the lease on its three different-sized Bestway sprayers. For approximately $3,700/yr., you can lease the company's large-capacity sprayer with a 1,000-gal. tank and a 60-ft. boom. At the end of five years, there is a 15% residual payment left of about $2,775.

"In essence, a farmer with 1,000 acres who sprays twice annually can own the sprayer for about $1.85/acre," says Bill Burdick, sales manager. For more information, contact RHS Inc., Dept. FIN, Box 394, Hiawatha, KS 66434, 800/247-3808.

Nozzle news Nozzles are more specific than ever to the job they perform. Specific products, crops, field location and environmental conditions influence nozzle selection, explains Kevin Humke, agricultural specialist for TeeJet Midwest, a division of Spraying Systems. He says growers need to decide before the application season whether they'll use a contact or a systemic product or even both.

With contact products, you need good coverage of the target weed to secure the best control results. A nozzle that places medium or small droplets in volume on the target usually does the best job.

Systemic product labels usually call for a coarse or very coarse droplet, because only a few droplets need to arrive on each plant for good control results. Also, some systemic products can require a higher degree of management to minimize drift, which has increased the use of spray management tips. Humke says the preorifice on these tips drops the pressure before the product is actually distributed, so coarse droplets result.

TeeJet Midwest offers a new threaded Turbo Turf Jet nozzle that is well suited to drift control. The quarter-male threaded tip offers a 125 degrees-plus tapered flat fan pattern and a range of 25 to 75 psi. Though geared toward the turf market, the nozzle works well in agricultural areas where potential drift is a concern. For more information, see the address for Spraying Systems below.

Wolf says software will soon be marketed to help farmers know how far a droplet will drift, based on the psi and nozzle type used and the product characteristics.

Because nozzles are as basic to a sprayer as oil is to a car, Marty Heyen, with Spraying Systems, recommends replacing them every year. On a 45-ft. boom, that's about 18 nozzles. At $6/nozzle, that's $108 and a considerable investment. However, even small misapplications are expensive.

If nozzles wear to a 10% flow increase from when they were new, that can result in a 10% misapplication. If treatment costs roughly $25/acre, overapplying by 10% will cost more than $1,200 on every 500 acres sprayed.

Underapplication is costly as well. "It can result in reduced pest control, costly resprays and lost profit potential," says Heyen, North American director for the company.

A common error with nozzles is poor spacing across the boom. Humke advises using a tape measure from center to center on the boom. "If the spacing is 20 in.," he says, "then every nozzle should be 20 in. from the next."

Controlling controllers Some growers who use automatic rate controllers depend on them to perform jobs beyond their ability. Marty Wagner, sales and service manager for Midwest Technologies, explains: "We're often asked if the controller makes a sprayer more accurate, and the answer is yes, as long as the sprayer is properly tuned and maintained," he says. "Incorrect controller set-up parameters, nozzle wear, uneven pressure distribution and ground-speed calibration are the kinds of things that can affect controller performance."

Humke agrees. He says that even with a controller, you can quickly go from an ideal spraying situation to one that's not. He says growers must maintain constant speed and pressure to prevent misapplications, and he offers this common scenario as proof: "Say you go down a steep hill and begin to pick up speed. If you start going above the recommended psi, you could suddenly go from applying a coarse droplet to applying a medium-sized droplet, which can open you up to a drift problem." The opposite can happen when you start up a hill. The result is that too little pressure is applied, and a misapplication occurs from product unevenly distributed across the boom.

There are a variety of control systems on the market. Capstan Industries retails a system called the Sharpshooter, Wolf says. The system ties the controller computer to spray nozzles, offering the flexibility of a four-fold flow rate. Farmers can dial in their spray volume to change rates without changing nozzles. "The technology offers both economic and environmental benefits," Wolf says. "In a lot of cases you don't need to blanket spray, and this system makes it practical to change rates quickly." For more information, contact Capstan Industries, Dept. FIN, 101 N. Kansas Ave., Topeka, KS 66603, 785/232-4477.

Spraying Systems offers a new wireless system, targeted primarily to custom applicators. The system allows you to use a personal computer in the comfort of your office to program the controller and application rates. For more information, contact Spraying Systems Co., Dept. FIN, Box 7900, Wheaton, IL 60189-7900, 630/665-5000.

Manage the boom Establishing the proper boom height can be tricky, even if you follow the guidelines in the manual. Manuals typically specify a minimum boom height. Humke says he likes to set the boom at least 4 in. higher than the minimum recommendation, because booms can't on their own hold a constant, specific height across the field. "As soon as the boom bounces and breaks that minimum height, there's a misapplication with too little overlap," Humke says. "The rougher the field, the higher you want to set that boom."

He adds that TeeJet Midwest recommends at least a 30% overlap in spray patterns. The more overlap, the better the spray distribution.

Calibration proclamation The fact is it still pays to calibrate. "Very few people do it," says Mike White, Iowa State University field crops specialist. "During pesticide applicator training meetings, I always ask who calibrates, and maybe five people in a roomful of 50 will raise their hands."

White advocates the use of the Redball spray tip tester, a plastic flow-meter device, which retails for around $40. In seconds, it can help you quickly calculate the flow rate of each nozzle. White says it takes about four seconds to check the gallons-per-minute output of each nozzle, and he can do 40 nozzles in less than three minutes. "It's quick and accurate," he says, except on very high or extremely low output levels. At those levels, you probably are better off using the traditional calibration jug collection method, which your local extension specialist can detail. For more information about the tester, contact Redball, LLC, Dept. FIN, Box 159, Benson, MN 56215-0159, 877/332-2551.

If you still think calibration is too much trouble, White offers these simple steps: "Spray 10 acres and see if the correct gallons per acre were applied by checking the tank fluid level. Then check your spray pattern and monitor end use."

When considering calibration needs, don't overlook the wheel speed sensor device. Depending on your system, it's either a radar, sonar or magnetic wheel device or a ground-driven device. For the magnetic wheel device, White says to calibrate it and place it on a non-drive wheel. "Don't put it on a wheel that drives the system," he says. "Wheel slippage will affect sensor speed."

Take care to mount the radar and sonar systems correctly so they provide the correct speed readings. White advises turning them backwards so they "shoot" to the rear. That prevents tall grasses or mud from affecting speed.

Fundamentals A little homework on sprayer fundamentals can help eliminate application mistakes, environmental concerns and unnecessary costs. Now is the time to consider your sprayer's overall condition, from its frame to its tires. A methodical check of each part to make sure it's clean, damage-free and in good working order will pay off in improved application. McPherson says he invests two hours each spring evaluating the condition of his equipment. "That covers about everything, and then I'm ready for the season," he says. For information about any company offering sprayers or components, go to Then click on I&T Product File, pull down the category Chemical Application Equipment and select a subcategory to locate companies.

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