Don't let the name fool you. The University of Missouri's WeedSOFT software program is anything but soft on weeds. It's designed to help farmers determine yield loss due to weed pressure. By 2002, producers will be able to use this tool in their ongoing battle against weeds.

In another year or two, your computer could be a major weapon for your war on weeds. University of Missouri researchers are testing and adapting a computer software program that helps growers evaluate weed pressure and decide which herbicides best suit their needs. In 2000, with experimental plots at Albany, Columbia and Novelty, Mo., Dr. Bill Johnson, weed scientist with University of Missouri Extension and the Commercial Agricultural Crops Focus Team, made the initial evaluation of the computer program.

"We also put the program out with about a dozen beta testers," said Johnson. "After the growing season, we critiqued the program, and we have made some changes to it."

The original version of the software was developed at the University of Nebraska (called "NebraskaHERB"). Johnson and his colleagues are adapting the program (called "WeedSOFT") to Missouri weeds, crops and growing conditions. Their goal is to help farmers, crop consultants, extension agronomy specialists and others make more accurate and more timely weed management decisions.

"WeedSOFT will be another tool for growers to use," said Lyndon Brush, MFA staff agronomist, who helped line up "beta" testers for the program last year. "And on down the road, I think this can be a valuable tool. It will let us take an advanced look at different aspects of weed control, including environmental concerns."

Both Johnson and Brush agree that WeedSOFT needs to be fine-tuned to more closely suit Missouri conditions. For the 2001 growing season, Johnson plans to have the software in the hands of 30 or more beta testers in all regions of the state. Brush is working to line up half or more of them.

WeedSOFT has several weed-management support modules, but Johnson and his team are concentrating on the modules that calculate expected yield loss for each weed species.

"We know that each weed has a competitive index, which can change with the environment or growing location," said Johnson. "For example, cocklebur, sunflower and giant ragweed are highly competitive with both corn and soybeans. Other weeds are relatively more competitive with either corn or soybeans."

By multiplying a weed's competitive index by the number of weeds in the field, producers can get an accurate estimate of that weed's effect on crop yield. But there's more to it than simply weed size, density and crop stage of growth.

The grower also enters soil type, pH, water table and other field conditions into the computer. Once fed this information, the computer generates a list of appropriate weed-control treatments from an existing database and predicts the efficacy of each compound or tank mix.

"A WeedSOFT user then can sort treatments for the highest percent maximum yield or the highest percent net gain," said Johnson. "Last year we found that about 80 percent of the efficacy predictions were extremely accurate. But errors in the other 20 percent of the program affected the overall accuracy of predictions."

In evaluating the 2000 results, Johnson found that two-thirds of the yield projections from the software program were accurate.

"The yield projections for low-yield environments were very accurate," Johnson noted. "In higher-yield environments, WeedSOFT's yield projections were off more. We are making changes to the program to improve the accuracy of projections in both low- and high-yield situations.

"Farmers are always looking for better tools to help them make decisions," he added. "We want this program to be as reliable as possible and believe WeedSOFT will be a good planning tool."

"One of our big questions has been about weed pressure," said Lyndon Brush. "That's a main thing we should take a closer look at in 2001. The program may need some fine-tuning to make it more regionalized to fit the different cropping areas of Missouri."

That's why Johnson and his team plan to study WeedSOFT for another year in more crop-growing regions of Missouri. He plans to have the program available across the state for the 2002 growing season.

Johnson expects the initial software to cost $100. Annual updates to include new or changed herbicides and tank mixes will cost about $30.