|
|
Asian soybean rust detected in Iowa field
At this point in the growing season, the rust shouldn't pose a problem on the crop since it is so far into maturity," said Iowa State University Extension soybean specialist Palle Pedersen. By Jennifer Bremer Asian soybean rust was found in a soybean field in central Iowa, but experts say it isn't a threat to this year's crop. Iowa State University Extension soybean specialist Palle Pedersen said samples from the suspicious plants found in a field near Dallas Center, were sent to the university for testing and confirmation came on Sept. 25. "At this point in the growing season, the rust shouldn't pose a problem on the crop since it is so far into maturity," he said. "Producers should also know that after a freeze, the fungus and spores that cause the disease will no longer be a threat." Soybean rust could cause damage to Iowa's late-planted soybeans, however. Soybeans that have reached R6 growth stage or later are at less risk. After R6, there appears to be no economic advantage to treating fields with fungicides according to David Wright, director of contract research for the Iowa Soybean Association. "We recommend that soybean growers scout fields with soybeans in the R4 to R6 growth stages to determine their overall risk," said Wright. "Most Iowa soybean fields are likely mature enough that producers need not spray this season." Plants must have green tissue present for the rust to thrive and survive. R6 is defined as full seed--pods contain green seed that fills the pod capacity at one of the four uppermost nodes on the main stem. Pedersen said the rust most likely came to the Iowa region on southerly winds, since the spores can travel in the air. While soybean rust seems to be more of a problem in the far South where rainy conditions are more prime for the spores to live, he said the conditions in Iowa have been prime this year as well. Recent cases of rust infection have also been discovered in Illinois, Kansas and Missouri. Rust was found earlier in the growing season in the many southern states including: Alabama, Georgia, South Carolina, Mississippi, Arkansas, Florida, Kentucky, Louisiana, Oklahoma and Texas.
Pedersen said even though Iowa has experienced rainy conditions this year, the rust problem didn't show up in Iowa until the end of September. "There are many other soybean diseases in Iowa to worry about that cause yield damage every year," he added. Fields that have been treated with fungicides should not be affected by the rust, however, Wright said producers should be aware that fungicides have a pre-harvest interval during which fields shouldn't be harvested. He suggested consulting a crop advisor if a problem is detected. Scouting for soybean rust includes determining the soybean growth stage and then looking for infected leaves in the lower canopy. Look on the underside of lower leaves for small volcano-like structures The opening of the structures will be round and will be more easily seen with a 20-30X hand lens. The Iowa Soybean Rust Team--which includes representatives of Iowa State, Iowa Department of Agriculture and Land Stewardship, the Iowa Soybean Association and the USDA Animal and Plant Health Inspection Service--has also recommended not spraying soybeans with fungicide once the crop has reached the full-seed stage. The Iowa Soybean Rust Team has recruited and trained more than 600 agribusiness professionals around Iowa to be "First Detectors" who can examine leaf samples and decide whether they warrant further analysis by ISU extension specialists or faculty scientists to detect possible infection. Soybean growers have been encouraged to work with First Detectors and consult with ISU Extension specialists on identification and management plans. Names and contact information for First Detectors are available on the Iowa Soybean Rust Team's Soybean Rust website, www.soybeanrust.info, and at county ISU Extension offices. Soybean rust infections in counties throughout the United States can be tracked at the following USDA website, www.sbrusa.net. Jennifer Bremer can be reached by phone at 515-833-2120 or by e-mail at jbremermaj@hotmail.com. Date: 10/3/07
Copyright/Privacy
Copyright 1995-2012. High Plains Publishers, Inc. All rights reserved. Any republishing of these pages, including electronic reproduction of the editorial archives or classified advertising, is strictly prohibited. If you have questions or comments you can reach us at High Plains Journal 1500 E. Wyatt Earp Blvd., P.O. Box 760, Dodge City, KS 67801 or call 1-800-452-7171. Email: webmaster@hpj.com |
|
