Spring is officially here! Not only is Minnesota greening up, but the EPA has granted our yearly Section 18 on tebuconazole which allows producers to manage Fusarium head blight (FHB/scab) on wheat and barley. I’d like to thank John Sierk, Minnesota Dept. Agriculture; Marcia McMullen, NDSU; and Diane Brown-Rytlewski, Michigan State Univ. for their help in obtaining this Section 18.

There are a number of tebuconazole products approved for application on small grains in Minnesota this year. They are:

1. Folicur 3.6F (Bayer CropScience)
2. Orius 3.6F (Makhteshim Agan of North America)
3. TebuStar 3.6L (Albaugh, Inc.)
4. Embrace 3.6L (Agriliance, LLC)
5. Tebuzol 3.6 F (United Phosphorus, Inc.)
6. Integral 3.6 (Luxembourg-Pamol, Inc.
7. Muscle 3.6F (Sipcam Agro USA, Inc.)

FHB epidemics depend on favorable environmental conditions for development with warm, wet or humid weather occurring before and during plant heading (barley) and flowering (wheat). Growing moderately resistant varieties and rotating out of small grains residue will reduce the risk for crop losses from disease. Minnesota growers should monitor the scab epidemic at least two weeks before a fungicide application is made (heading for barley; early flowering for wheat). The website will assist growers in determining whether a fungicide application is needed. The forecasting website is at:

 http://mawg.cropdisease.com/

This year, an EPA Section 3 registration for the use of Proline 480 SC in small grains has been obtained to manage disease issues such as tan spot, septoria and FHB in wheat or net blotch, spot blotch, and FHB in barley. Bayer CropScience is supporting tank mixing their two triazole products (Folicur and Proline) for increased management of FHB over either single active ingredient product.

Testing has been done on the efficacy of Folicur (active ingredient: tebuconazole), Proline (active ingredient: prothioconazole), and various tank mixtures of both active ingredients (tebuconazole and prothioconazole). Rates of active ingredients vary from test to test with tebuconazole (Folicur) usually being tested at a lower comparative application rate, thus it’s at a disadvantage. Keeping this in mind, results by year and cropping species are shown in the accompanying graphs.

 
  Graphs summarizing Wheat Studies,
2003 - 2006

 

  Graphs summarizing Barley Studies,
2004 - 2005

Results summary:

Wheat.

Folicur resulted in significantly less yield compared to mixes of active ingredients in 2 of 4 years and significantly more DON accumulation in 1 of 4 years. Prothioconazole resulted in greater yields compared to Folicur in 1 of 2 years and less DON accumulation in 1 of 2 years. The overall trends were for less DON accumulation and increased yield with the prothioconazole and Folicur + prothioconazole mix treatments compared with the Folicur treatment.

Barley.

No clear trend was apparent. Barley varieties have little resistance to FHB and an efficient disease management strategy is difficult to achieve without an integrated management approach.

Economic analyses were not conducted from 2003-2006, since prothioconazole was not priced for the marketplace.

Need a copy of small grain fungicide labels ? You can find them here . . .
http://nwroc.umn.edu/Fungicides/fungicide_labels.asp

Charla Hollingsworth, Plant Pathologist
University of Minnesota