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Corn+Soybean Digest

Brock Online Notes

Fears Of Rust Spread Said Overblown

Fears that tropical storm Arlene carried Asian soy rust spores from the southern U.S. into the Midwest were probably unfounded, plant pathologists told Reuters News Service Friday.

As a precaution, crop scouts in Ohio, Indiana and Missouri were inspecting soybean fields this week for signs of the crop-devastating fungus.

Anne Dorrance, a plant pathologist at Ohio State University, compared the amount of spores Arlene might have carried to throwing a few grains of sand into an ocean.

"It would be so dilute," she says. "The big unknown is how many, if any spores, were in the storm." The eye of tropical storm Arlene hit last weekend west of the five counties in Florida and southern Georgia where the USDA confirmed soy rust.

“It didn't directly go over where the spores have been positively identified," says Shawn Conley, an agronomist at Purdue University. "We were fortunate."

If Asian rust has come to the southern Midwest, the first symptom crop scouts will see is tiny black spots on the underside of soybean leaves in the next seven to 10 days, experts say.

Even pre-Arlene, Indiana was making daily inspections of the state's 10 sentinel soybean plots, which were in the late vegetative to flowering stage. "They're big enough now to show symptoms if rust came," says Ray D. Martyn, professor of plant pathology at Purdue.

Rust typically surfaces from the flowering stage onward, but can appear earlier. Martyn says he believes Indiana and other northern soybean states are in danger only if there was more soy rust in Florida and Georgia than reported.

Editors note: Richard Brock, The Corn and Soybean Digest's Marketing Editor, is president of Brock Associates, a farm market advisory firm, and publisher of The Brock Report.

To see more market perspectives, visit Brock's Web site at

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