Special Edition   April 24, 2009

STORAGE MOLDS IN FEED GRAINS AND HAY

Potential for Moldy Stored Grain or Hay

Grain or hay harvested at high moisture contents last fall and not adequately stored or dried may have higher risk of storage molds this spring. Storage mold fungi may result in poor feed quality and possible development of mycotoxins. For example, corn or wheat grains and silage infected with one or more species of Fusarium fungi going into storage could have produced mycotoxins such as vomitoxin and zearalone in storage - if storage moisture and temperatures remained high and fungal growth occurred.

Risk of Using Moldy Feeds

The safest recommendation is to NOT use mycotoxins-contaminated or moldy feed and hay. Feed grains and hay may be tested for common mycotoxin contaminates by the NDSU Veterinary Toxicology Lab or other grain testing laboratories, but some unknown or uncharacterized mycotoxins could still be present and not detected by the commonly used analytical methods. IF moldy feed must be used, it should be fed only to animals that are less sensitive to potential adverse health effects of mycotoxins, e.g. feeder animals. Moldy feeds should not be fed to pregnant or lactating animals.

One Source for Testing Moldy Feed Grains and Hay: NDSU Veterinary Diagnostic Lab Testing Facility

Information on type of sample needed, cost of testing, and on the specific mycotoxin analyses done by the NDSU Veterinary Diagnostic Lab may be found at: http://www.vdl.ndsu.edu/, or the NDSU lab can be reached by telephone at (701) 231-8307 or by email at: vdladmin@ndsuext.nodak.edu.

Links to Other Information on Use of Moldy or Mycotoxin Contaminated Feed

Detailed information about feeding moldy or mycotoxin contaminated grain and hay may be found at the following Internet sites:

DON (Vomitoxin) in Wheat (North Dakota State Univ.)
http://www.ag.ndsu.edu/pubs/plantsci/pests/pp1302.pdf

Use of Feed Contaminated with Fungal (Mold) Toxins (Mycotoxins) (Univ. of Nebraska)
http://elkhorn.unl.edu/epublic/pages/publicationD.jsp?publicationId=343

Moldy Grains, Mycotoxins and Feeding Problems (Ohio State Univ.)
http://www.oardc.ohio-state.edu/ohiofieldcropdisease/mycotoxins/mycopagedefault.htm

Mold and Mycotoxin Problems in Livestock Feeding (Penn State Univ.)
http://www.das.psu.edu/dairy/nutrition/pdf/mold.pdf

Greg Lardy
NDSU Extension Livestock Specialist
gregory.lardy@ndsu.edu

Marcia McMullen
NDSU Extension Plant Pathologist
marcia.mcmullen@ndsu.edu

 

FUNGICIDE SEED TREATMENTS AND 2009 PLANTING CONDITIONS

Less than ideal planting conditions (floods, waterlogged soils, cold temperatures) may challenge the establishment of crops this summer. One common concern plant pathologists have in these conditions is the loss of stand and yield due to seedling blights and root rots. This article is meant to briefly explain root rots, the conditions that favor them, and fungicidal seed treatments.

Will we see root rots in 2009?

The 2009 growing season is getting off to a late start, and seed bed conditions may be less than optimal. Poorly drained and wet soils, or cold, soils will slow germination of crops and favor activity of many soil-borne pathogens. Examples of fungi that can cause seed and root rot under wet, cold conditions include various Pythium species that attack many crops, the Phytophthora root rot fungus of soybeans, and the downy mildew fungus that attacks sunflower. If the soils become warmer, but are still wet, these conditions favor infection by a number of other soil-borne fungi, such as the common root rot fungus on small grains, and the Fusarium and Rhizoctonia root rot fungi of multiple crops. Re-occurring wet conditions following germination and emergence also favor root rot development.

Even if soil conditions improve later in the season, early infections may still rob yield. Sometimes the greatest yield loss from root rots occurs in years that begin wet and become dry. When water is abundant (wet soils) even an infected root system may be able to extract enough moisture for the plant. However, when the soil becomes dry, a diseased root will not likely have the ability to extract enough moisture to reach maximum yield potential. Additionally, Fusarium and Rhizoctonia may continue to develop even when soil begins to dry, which will exacerbate the problem.

Seed Treatment Options

Fortunately, there are many broad-spectrum seed treatment fungicides now available that protect against soil-borne fungi, as well as protect against seed-borne diseases. Many contain mefenoxam or metalaxyl fungicides, which protect the seedling against water mold fungi such a Pythium or Phytophthora, plus contain a fungicide such as a triazole or strobilurin , that acts against most fungi other than the water molds. A product that contains a combination of chemicals with different targets (a broad-spectrum seed treatment) generally is recommended under these disease favoring conditions. Otherwise, a mix of single acting products may be needed. See the accompanying Quick Guide to seed treatment fungicide common names and their activity against some major soil-borne fungi. Some commercial products contain two or more of these fungicides, others may contain only one.

Small Grains: Some of the broadest spectrum fungicide seed treatments registered for wheat and barley include: Dividend (difenoconazole + mefenoxam), Cruiser Maxx (difenconazole + mefenoxam + thiamethoxam insecticide), Raxil or Dyna Shield (tebuconazole + metalaxyl), Raxil MD Extra W (tebuconazole + metalaxyl + imidacloprid insecticide), and Charter PB (Triticonazole + thiram). All of these products protect against multiple root rots, seedling blights and loose smut, and several have protection against soil borne insects, such as wireworm.

Response to use of these seed treatments has generally resulted in stand improvements across a wide set of environmental conditions, and wheat yield increases of 2-6 bushels, on average. Seed treatment costs vary, but range up to $2.00/bushel depending on manufacturer and disease spectrum of the product.

Broad-leaf crops: Field history, such as continuous cropping, short rotations, and a history of root rot problems increase the risk of root rot problems in broad-leaf crops, many of which have similar root pathogens attacking across multiple crops. Poorly drained soils or cold, wet soils also delay crop emergence and favor growth and infection by these root rot fungi. When choosing a fungicide seed treatment for broad leaf crops, it generally is best to apply a broad-spectrum product with activity against Pythium and Phytophthora (mefenoxam or metylaxyl) and Fusarium and Rhizoctonia (azoxystrobin , trifloxystrobin, and fludioxonil for example), or a mixture of single product ingredients may be needed.

In a recent two-year (2003 and 2004), fourteen location ND soybean fungicide seed treatment study, the average yield increase was 2 - 4 bushels per acre, depending on treatment. At $10 soybeans, that would translate into a $20-40/acre return on investment, minus the cost of the treatment. However, that data was averaged over two very different environments. In a dry spring (2003), no yield increase was observed in any of the six locations, but in a wet and cool spring (2004), a statistically significant yield increase was observed in four of the eight locations. Additionally, statistically significant increases in stand and reductions in disease were observed in two additional locations. Thus, the potential return on a seed treatment may be even higher in a cool and wet spring.

Need More Information?

Most seed treatment products are registered for on-farm use, either for drill box application or to be applied in a mist or slurry with an auger treater. For information on current seed treatment products registered on all crops in North Dakota, check the 2009 North Dakota Field Crop fungicide Guide (Extension Circular PP-622) available at http://www.ag.ndsu.nodak.edu/extplantpath/

Always read the label carefully and follow the label directions for application procedures, rates, and specific diseases controlled.

Quick Guide Examples: Soil or Seed-Borne Activity of Some Newer Seed Treatment Fungicides on Small Grains or Broad-leaf Crops (not potato or sugarbeet).

Common Name of Active Ingredient in Products*

Water mold fungi

Other Root Rot fungi

Pythium
S
mall grains & Broad-leaf crops

Phytopthora in soybean

Downy mildew in sunflower

Common root rot - Small grains

Rhizoctonia and Fusarium root rots

Small grains

Broad-leaf crops

Azoxystrobin

X

X

X

Difenoconazole

     

X

X

 

Fenamidone

   

X

     

Fludioxonil

       

X

X

Mefenoxam

X

X

       

Metalaxyl

X

X

       

Tebuconazole

     

X

X

 

Trifloxystrobin

         

X

Triticonazole

     

X

X

 

Multi-spectrum products generally have two or more active ingredients within a trade-name formulated product.

Not all products may be registered in all crops. Please consult the ND Field Crop Fungicide Guide (NDSU Extension Circular PP-622 (http://www.ag.ndsu.nodak.edu/extplantpath/) for more information.

Marcia McMullen
NDSU Extension Plant Pathologist
marcia.mcmullen@ndsu.edu

Sam Markell
NDSU Extension Plant Pathologist
samuel.markell@ndsu.edu


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