By TIM ALEXANDER
Illinois Correspondent URBANA, Ill. — A early warning system for detecting the presence of Asian soybean rust in Illinois fields is again in place this year.
Some 40 “sentinel plots” along with 28 spore traps are being monitored by experts from the University of Illinois (UOI), Southern Illinois University (SIU) and certified crop consultants and farmers for the presence of the disease.
Soybean rust is expected to reappear in Illinois by harvest.
“The plots are part of a national surveillance system initially established during 2005 in more than 30 soybean-production states throughout the eastern and Midwestern sections of the country,” said Linda Kull, program coordinator for the National Soybean Research Laboratory at UOI-Urbana. “The network is designed to track the establishment and movement of soybean rust during the growing season and provide timely information for effective management decisions.”
Researchers involved with the project agree that it’s not a matter of if rust will reappear in Illinois in 2007, but rather of where and to what extent.
“Most pathologists assume and are preparing for (rust) to show up again this year, however the weather in the South will dictate if and when the disease will show up in 2007,” said Jason Bond, SIU associate professor in the plant, soil and agriculture systems.
“Last year it showed up in the extreme southern counties of the state. Disease prediction models indicate this was due primarily to a weather system that transported the spores from Louisiana to Illinois. In my opinion, farmers in the Midwest would benefit if it stayed dry in the South.”
Glen Hartman of USDA-ARS and UOI said rust was identified in southern Illinois in October of last year, and the same scenario is likely to repeat itself.
“It could come earlier, but not early enough to cause great damage,” he added.
Bond said the 40 sentinel plots are spread across the state and located on both public and private sites. Ten are located on research stations owned by SIU, UOI and Rend Lake College; five are located on land used by seed companies and 25 are situated on privately owned farms.
Hartman said the plots are usually 30-foot by 30-foot or 50-foot by 50-foot.
Field inspectors include UOI and SIU researchers and research farm managers, the UOI Extension and certified crop consultants, along with a few farmers.
“Field inspectors visit plots bi-weekly and then weekly after flowering begins,” Hartman said.
“Leaf samples are taken and sent to the plant disease clinic at UOI where they are put under a microscope and analyzed, then entered into a national database.”
Analyzing the samples is the task of clinic director Nancy Pataky and her team.
“The first positive sample found each year must be sent to the APHIS (USDA) for confirmation before an announcement can be made. Prior to sending a suspected sample, Nancy alerts the authorities at the Illinois Department of Agriculture, the Illinois Soybean Assoc. and other agencies that a sample was sent for confirmation,” Bond said. “After the first report the director can change the counties from ‘green’ to ‘red’ without having to send away samples.”
Greenhouse studies have shown that soybean plants can be infected at any age under the right conditions. However, in the field environment the symptoms of the disease and the signs of the pathogen are generally not seen until the R1, or flowering, growth stage. Plants showing symptoms at R1 would actually be infected 12-20 days earlier.
A worst-case scenario for rust encroachment would be infection during the soybean plant’s potting stage, Hartman said, adding that if you were to put an infected plant in a large soybean field it could spread the disease throughout the entire field within a month.
“The disease can move very fast within a field or a county,” said Bond. “Also the fact the pathogen is in the plant for several days before you know that plants are sick (latency) also contributes to fast deterioration of the crop. How fast is dictated by the percentage of plants infected when the spores were deposited in the field and the weather conditions prior to and after the plants are infected. One to two weeks after infection the pathogen can begin producing spores on the newly-infected plants, so there are several critical time periods that adequate rainfall or moisture is needed.
“In most years, we will probably not have the type of rainfall patterns that will allow every single field to be devastated by the pathogen in this state. However, the pathogen can still reproduce and spread its spores under limited rainfall. Foggy mornings, extended dew periods, etcetera can provide moisture for the pathogen to cause disease and spread.”
Kull said the national rust surveillance system has been expanded to include other hosts and pests and a recently updated Good Farming Practices Documentation Tool.
“This tool will assist producers in substantiating that good farming practices were used to manage soybean rust. Good documentation of early detection and treatment is very important should producers need to file an insurance claim,” Kull said.
The expanded program is known as the Pest Information Platform for Extension and Education (PIPE).
“PIPE serves as an online, real-time observation and forecasting system that allows growers to access the latest information about which states have confirmed the presence of soybean rust,” said Carl Bradley, plant pathologist with the UOI Extension. “The system tracks the spread of soybean rust, as well as soybean aphids, in soybean fields across the state. Growers can sign up to receive e-mail notifications of soybean rust confirmations across the nation.”
Nation reports on the discovery of soybean rust are available at www.sbrusa.net
Reports from Illinois sentinel plots and spore traps can be found at www.soybeanrust.org This farm news was published in the June 13, 2007 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee. |
