Over the past couple of weeks, a number of phone calls have been received asking if Section 18 (emergency exemption) fungicides can be sprayed in Iowa. The answer is "yes," Section 18 fungicides may be used in Iowa; however, the Section 18 label clearly states that the products only are approved for the management of Asian soybean rust (ASR). That is, they are not approved for control of other foliar diseases if rust is not present or conditions do not favor ASR development.
Fungicides with Section 18 labels for Iowa include:
- myclobutanil (Laredo 25 EC, Laredo 25 EW)
- propiconazole (Tilt® 3.6 EC, PropiMax 3.6 EC, Bumper® 41.8 EC)
- tebuconazole (Folicur® 3.6 F, Orius 3.6 F)
- tetraconazole (Domark 230 ME)
- propiconazole and azoxystrobin (Quilt®)
- pyraclostrobin + tebuconazole (Headline® SBR), and
- propiconazole + trifloxystrobin (Stratego®)
These fungicides do not currently have a full federal label (Section 3) for use on soybeans because they have not gone through the risk analyses required to ensure residues on the crop are within acceptable limits for food safety purposes. However, because soybean rust has been reported in the continental United States, and because this disease has the potential to result in significant economic damage, the Iowa Department of Agriculture and Land Stewardship petitioned the Environmental Protection Agency for emergency exemption labels to control the disease. It is very important that we follow the directions on the Section 18 labels. Failure to do so will jeopardize approval of requests for future Section 18 exemptions.
A few people also have asked whether ASR must be found within Iowa before the Section 18 fungicides can be legally applied in our state. The answer is "no." These Section 18 fungicides became approved for use in managing ASR in Iowa when the discovery of ASR in Louisiana was announced on November 10, 2004. However, these products cannot be used until rust is present or conditions favor ASR development in Iowa, which is not the case currently.
Asian soybean rust has NOT been found in Iowa, and the risk of Asian soybean rust occurring in Iowa at the time this article was submitted for printing is minimal. Therefore, spraying soybeans with a fungicide is not recommended at this time. Please continue to check www.soybeanrust.info for the latest information on Asian soybean rust. Rest assured that if we believe a fungicide spray is necessary, you will be advised in a timely manner.
This article originally appeared on page 3 of the IC-494(17) -- July 5, 2005 issue.