Integrated Crop Management

Questions concerning Section 18 fungicides

During the winter, Iowa State University Extension staff and the Iowa Department of Agriculture and Land Stewardship (IDALS) Pesticide Bureau staff fielded questions about Section 18 (emergency exemption) fungicides to decide whether Iowans can legally spray them for management of Asian soybean rust (ASR).

In 2005, the Iowa Soybean Rust Team formulated the "I-70 Rule." They recommended that Section 18 fungicides not be sprayed unless Asian soybean rust was found north of I-70 in Missouri.

Recent guidance from the Environmental Protection Agency (EPA) regarding the interpretation of Section 18 label instructions and application timing has led the team to no longer recommend the "I-70 Rule." Under current Section 18 labeling, a grower or applicator is permitted to apply Section 18 soybean rust fungicides in accordance with all label instructions when the grower or applicator determines it is necessary for managing Asian soybean rust.

Can Section 18 fungicides 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 are approved for the management of ASR only. That is, they are not approved for control of other foliar diseases or plant health benefits.

Can Section 18 fungicides be legally sprayed in Iowa before soybean rust is found in Iowa?

Again, the answer is "yes." This answer is different from what was given last year.

What exactly is a Section 18 fungicide and which ones currently carry this label?

Section 18 fungicides are pesticides temporarily exempt from registration under the Federal Insecticide, Fungicide and Rodenticide Act based on an emergency condition that may cause a significant economic loss by a particular pest problem. During their review of applications for Section 18 emergency exemptions, EPA staff must perform risk assessments related to pesticide exposures through diet, workplace, and the environment. The Food Quality Protection Act requires that a time limited tolerance must be established for each active ingredient. To establish this tolerance, EPA must find that there is reasonable certainty that no harm will result from the use of the pesticide as labeled.

Because ASR has been detected in the continental United States and because this disease has the potential to result in significant economic damage, IDALS petitioned the EPA for emergency exemption labels to control the disease. The following is a list of Section 18 authorizations received from EPA to date for managing soybean rust in Iowa:

Product Active Ingredient
Laredo 25 EC, Laredo 25 EW myclobutanil
Tilt 3.6 EC, PropiMax 3.6 EC, Bumper 41.8 EC propiconazole
Folicur 3.6 F, Orius 3.6 F, Uppercut tebuconazole
Domark 230 ME tetraconazole
Quilt azoxystrobin + propiconazole
Headline SBR pyraclostrobin + tebuconazole
Stratego trifloxystrobin + propiconazole

Are there any other new products available in 2006?

In April 2005, IDALS petitioned EPA for additional emergency exemptions. EPA has not made any decisions on the following products but expects to do so during the 2006 growing season:

Product Active Ingredient
Alto 100 SL cyproconazole
Quadris Xtra 2.34 SC azoxystrobin + cyproconazole
Punch 3.3 EC flusilazole
Charisma 1.7 EC flusilazole + famoxadone
TopGuard 125 SC flutriafol
Caramba 90 SL metconazole
Headline-Caramba co-pack pyraclostrobin + metconazole
Proline 480 SC prothioconazole

So when should I spray?

Growers or applicators are encouraged to work with their Iowa State University Extension specialists in determining the best approach for managing soybean rust with fungicides. Iowa State University Extension is developing a publication that offers producers some tips on how to manage Asian soybean rust with fungicides if ASR reaches Iowa this crop season. We expect to have this publication, Asian Soybean Rust Management--2006 (PM 2028), available in late April.

This article originally appeared on page 80 of the IC-496 (6) -- April 10, 2006 issue.

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