"I understand it 100%, but I don't recommend it." That's how Bill Wiebold, University of Missouri Extension agronomist sums up his stance on whether soybean producers in northern and central Missouri should plant an early-maturing variety as a hedge against Asian soybean rust.

"The strategy might work in some southern states, but there's little data upon which to base predictions of what would happen in Missouri," he said in an MU release.

By planting Maturity Group I or II soybeans - varieties that usually are grown in Iowa and southern Minnesota - the goal is to have the crop further along in the seed-filling process should soybean rust move into a field, Wiebold says.

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"This seems to make sense because we know soybeans stressed during mid-seed filling suffer less yield loss than plants stressed at the beginning of pod development," he says. "However, Group I and II soybeans planted in Missouri will be shorter, branch less and have smaller leaf areas than adapted varieties, so their yield potential will be less."

Wiebold recommends producers focus on maximizing their soybean yield potential instead.

"Do the best job of growing soybeans that you can," he says. "The threat of rust makes everyone nervous, but don't make a management decision based solely on the rust. You risk hamstringing your crop when we don't really know how big of a problem rust is or isn't going to be."

Wiebold also points out that as producers read or hear about rust-avoidance strategies in the media in the coming months, they need to be aware that many recommendations will be region-specific.

"What's best for Mississippi or northern Illinois or wherever will be different than what's best for Missouri, so you really need to know where they're talking about in a TV news story or magazine article," he said.

Planting Group III instead of Group IV or V soybeans might be an appropriate strategy on some acreage in southeast and southwest Missouri, Wiebold said. However, "yield variation is likely to be greater" from year to year.

"The crop will be more susceptible to varying environmental conditions, so predicting yield will be more difficult," he says. "It will also be maturing when it's hot and humid, increasing a risk of reduced grain quality from seed-borne diseases such as phomopsis."

Some central and northern Missouri producers may consider planting earlier to avoid rust, Wiebold said. "I don't think it'll have much impact, but there is a little yield bump to be gained from getting your beans planted in early May rather than mid- to late May."

Another risk? Planting soybeans early can subject the crop to conditions that are favorable for infection by sudden death syndrome.

"It's not recommended that you plant early in fields with a history of SDS," he says.

StopSoybeanRust.com is a Web site with information and resources about Asian soybean rust, created by the Greenbook, Dealer & Applicator magazine and Successful Farming magazine. It is sponsored by Bayer CropScience US. Content is provided by a variety of sources including the United Soybean Board and the Crop Advisor Institute.