The newest version of a computer weed control decision aide will help farmers do more than choose the best herbicide, said a University of Missouri weed scientist.

“WeedSOFT 2003 can help you choose the most cost-effective herbicide for the weeds you have,” said Brent Sellers, MU graduate student who has helped modify the software for Missouri conditions.

“It can also tell you a lot about what will happen if choose to control those weeds or not. Winter is the perfect time to key in the information for fields you'll be planting in the spring.

“And it's a great time to play ‘what if’ games with the software and test weed management strategies.”

Weed control decision tools for wheat and for grain sorghum are two new features of WeedSOFT 2003. Those tools, plus databases for corn and soybean weeds, are part of Advisor, the most popular module of software.

In Advisor, the user lists the weeds to be controlled, weed populations and growth stages, type of crop, expected yield, grain price and other information. The software then calculates herbicide mixes that would control those weeds, their cost, and the overall economic outcome of controlling the weeds at that point.

“The software comes with standard pricing for herbicides and mixes, but you can also input the prices quoted from your local retailer,” Sellers said.

The software calculates what weed control would cost versus the yield damage that would occur if the weeds were not controlled. “That can be a real education,” Sellers said.

To illustrate that point to farmers at a recent MU conference, he and Lyndon Brush, agronomist with MFA Inc. in Columbia, Mo., created a fictitious corn field with foxtail, waterhemp and cocklebur. Brush selects a herbicide mix costing $20.34 per acre. If applied to weeds 2 to 4 inches tall, the mix shows 95 percent or better control of the broadleaf weeds, 60 percent control of the foxtail. Spraying the field returns an estimated $16.16 per acre above the herbicide and application costs.

Waiting until those weeds are 4 to 8 inches tall changes the picture. Weed control drops to 74 percent to 77 percent on broadleaf weeds, 47 percent on foxtail grasses. Net return is $14.41.

“There is still a benefit to the herbicide application, but you're also missing some weeds that may add to the weed seedbank in the soil for future seasons,” Sellers said.

The software also helps spot potential environmental problems. For example, it alerts the user when a herbicide mix can't be used near creeks, ponds or other sensitive areas.

Decisions presented by the software are based on weed control data from University of Missouri field tests. WeedVIEW, the second module in the software, is a photo database of 64 weed species to help farmers identify which weeds they are trying to control. Software versions for Kansas, Illinois, Indiana, Nebraska and Wisconsin are also available.

WeedSOFT 2003 costs $195. It works only on Windows-based computers with Windows 95 or newer, requires a CD-ROM drive and must have 16 megabytes of RAM memory minimum. The program needs 80 megabytes of hard disk space during installation, and takes up 20 megabytes of space once installed.

Order from Bulletins, P.O. Box 830918, Lincoln, Neb., 68583-0918. You must specify which state version you want and include your e-mail address to receive notification on software updates.

A demonstration version, which includes fewer potential herbicide treatments and lacks the WeedVIEW module, is available for $5 from Sellers at 210 Waters Hall, Columbia, MO 65211. Make checks payable to University of Missouri.

“This software is a support system; it's one tool to help you make weed control decisions,” Sellers stressed. “It's not foolproof, and it shouldn't be the sole reason for making a particular decision during the growing season. But it can help you sort through options and help you decide which ones might be best for your situation.”


Greg Horstmeier is news director, Extension & Ag Information, University of Missouri (573-884-1846, horstmeierg@missouri.edu).