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Asian soybean rust (ASR)
Soybean Rust Publications
ExEx 8155 Managing Soybean Rust in South Dakota in 2006
ExEx 5057 Crop Insurance and Soybean Rust
2005 Asian Soybean Rust Tabloid (pdf)
Current Areas in the US in 2004 with Confirmed Soybean Rust
SDSU expert: Brace for Asian soybean rust
Asian soybean rust will be the next major plant disease threat South Dakota producers should watch for, a South Dakota State University specialist said.
The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has confirmed Asian soybean rust on soybean leaf samples from Louisiana. Additional confirmations are expected in other Gulf states.
SDSU Extension Plant Pathologist Marty Draper said itÂ’s unclear how much of a problem soybean rust will be in the northern Great Plains, but he said South Dakota producers will have to monitor their fields for rust starting with the 2005 growing season.
There are two weather issues that may relate directly to the potential severity of soybean rust in South Dakota, Draper said. Those issues are the winter weather in Louisiana and the spring weather in South Dakota. Based on this 2004 introduction, the chances are better than fair that soybean rust will be blown to South Dakota in 2005.
While the official winter outlook is for warmer than average temperatures in South Dakota and the western United States, the El Nino phenomenon that climatologists are currently monitoring typically brings cooler and wetter conditions to the Gulf Coast, according to SDSU Extension climatologist Dennis Todey. These effects will confuse the issue of overwintering further.
More likely it will survive farther south, but the farther north the spores originate from, the greater the risk to South Dakota,Draper added.
USDA-APHIS will be surveying the Gulf Coast in the coming weeks to determine the actual risk.
Once the spores are blown northward, the disease still needs an environment that will favor infection and disease progress. If weather is hot and dry, the chances of having a severe epidemic are reduced. On the other hand, moderate temperatures with overnight dews could lead to rapid increase of the pathogen.
If soybean rust gets to South Dakota, fungicides will have to be used to manage the disease. Fungicides are effective against the disease if they are applied correctly and in a timely manner.
Soybean rust is another disease, like potato late blight, where playing catch-up is not a good disease management strategy, Draper said. Even the curative fungicides, the triazole fungicides like myclobutanil (Laredo), propiconazole (Tilt, PropiMax and Bumper), and tebuconazole (Folicur), that have been approved for conditional use, are not highly effective in a severe outbreak.
Protectant treatments currently labeled include azoxystrobin (Quadris) and chlorothalonil (Bravo, Echo). The cost for treatment will range from $6 to $15 product cost per acre. An additional $3.50 to $5 per acre should be budgeted for application costs. Some potential problems with the fungicide effectiveness include poor timing of the treatment, poor canopy coverage, and incorrect choice of products for your situation (spraying a protectant in a curative situation).
Multi-peril crop insurance will cover losses from rust if the producer has done the best he could to control the disease, Draper said. That makes it essential for producers to actively scout fields to monitor for disease development.
I would recommend that producers in eastern South Dakota consider budgeting for a fungicide application. If the treatment is not budgeted, it is very difficult to make the decision to spray, but if you don't need it, it is far easier to cancel.
Draper added that producers should not count on having resistant varieties in the near future.
My best guess would be that 10 to 15 years is a best-case scenario. Sources of "durable resistance" (multigenic sources that reduce the rate of disease progress) are just in the early stages of identification, Draper said. It will take another two years to rate those possible lines and evaluate if they provide adequate resistance. Even then, I expect that fungicides could be needed in some years, depending how early the rust spores blow into South Dakota and how favorable the environment is for disease development in a given year.
Lance Nixon, Editor
AgBio Communications Unit
South Dakota State University
Fungicide Use Guidelines for Asian Soybean Rust (pdf)
Recognizing and Identifying Soybean Rust (ppt)
Soybean Rust Dispersal
Soybean Rust Fungicide Best Practices
Table of fungicides approved for use in SD (pdf)
Table-soybean rust_mod SD 15 May 2006
Today's Ag segment on soybean rust (wmv)
Other Links
APHIS soybean rust website
Asian Soybean Rust - Iowa State University
Complete news release regarding the recent soybean rust detection
Facts about Soybean Rust Fungicide Best Practices
PEST ALERT: Soybean Rust
Soybean Rust Q & A
Soybean Rust: Issues and Facts
Stop Soybean Rust
Economic and Policy Implications of Wind-Borne Entry of Asian Soybean Rust into the United States (USDA-ERS) pdf
Soybean Rust Pest Alert pdf
Soybean Rust pocket card pdf
Soybean Rust, Missouri Extension (pdf) pdf
Contact Info
Larry Osborne, SDSU Extension Plant Pathologist
(605) 688-5543
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Plant Science Department, South Dakota State University |