Hoegemeyer - the right seed

Several questions are circulating around this year in regards to ear molds/kernel rots and potential for alfatoxin production in drought stressed fields. Here are a few details describing the specifics pertaining to aflatoxins.

Aflatoxins are a subgroup within a larger more general group called “mycotoxins”. Several ear rots and storage molds which occur every year to some degree are capable of producing mycotoxins. The term “mycotoxins” refers to “toxic chemicals” in a broad general spectrum including aflatoxins, fumonisins, tricothecenes, and zearalenone, some of which are much more problematic than others. Just because an ear and/or kernel mold is visually present does not necessarily confirm the presence of a mycotoxin or more specifically aflatoxin. Aflatoxins are a specific group of mycotoxins that get significant attention due to their potential to be relatively toxic to livestock and humans at varied levels. The specific B1 aflatoxin is also a known potent carcinogen which especially draws attention for regulation. Aflatoxins are produced by at least two species of Aspergillus. This kernel/ear mold is recognized by its somewhat olive green color. Although the presence of the mold indicates a higher risk of aflatoxin production, aflatoxins are not automatically produced when grain becomes moldy.

Environmental conditions will dictate if and at what level aflatoxins are produced. Problems associated with Aspergillus and aflatoxins are most common in hot, dry years (I think the summer of 2012 would fit that description).  Fungi survive in plant residue from prior years. The fungi does best in corn from silking through grain fill when drought conditions are present during hot days and warm nights.  The spores are carried by the wind and can enter the ears through injury caused by insect feeding, hail, drought, early frost and high wind which help to expose kernels to the fungus.   In summary, if Aspergillus is readily evident within a field, aflatoxin production is definitely more likely considering the conditions we had this year. Those fields under high suspicion should likely be evaluated and managed separately. The following are some steps that can be taken to manage or reduce aflatoxins in grain:

1)  Control ear-attacking insects.
2)  Scout. Indentify early. If present, early harvest and drying of grain can help reduce further development.
3)  Adjust combine to minimize kernel damage.
4)  Clean grain bins and handling equipment.
5)  Dry moldy corn immediately to 15% or less moisture when storing in the short term. Long term storage is not suggested.
6)  Cool grain after drying and maintain at 35-40 degrees F through winter.
7)  Control storage bin insects.
8)  Check bins regularly.

Fig. 5.7 Yellow-green powdery growth of Aspergillus flavus on a corn rootworm-damaged corn ear can produce aflatoxins. Courtesy of Alison Robertson, Iowa State University.

The FDA has suggested recent exemptions to the long-standing action level of 20 ppb. They are as follows:

Human food and milk <0.5 ppb

Corn of unknown destination <20 ppb

Young animals <20 ppb

Dairy cattle <20 ppb

Breeding cattle, swine, and mature poultry <100 ppb

Finishing swine <200 ppb

Finishing cattle <300 ppb

Elevators will likely have their own testing protocols as well as tolerance levels depending on where the grain is being channeled to for end use.

      Sources:    Iowa State University
       Hoegemeyer Hybrids Agronomy

Hopefully aflatoxins will not be a problem in your fields but be prepared and have a plan of action if you have concerns.  If you have further questions, contact your local Hoegemeyer Agronomist of District Sales Manager. 
 

Be on the lookout for Goss’s Wilt!  Several area agronomists have indicated seeing Goss’s Wilt showing up in some fields they are overseeing.  This is not real surprising as many areas in the Western Corn Belt have experienced weather conditions such as wind, sand blast, hail and other plant injuries that may open the door to let the Goss’s Wilt pathogen enter into the plant.  This problem can really be enhanced in fields that received early storm damage, are corn on corn, had a Goss’s Wilt presence before or have a lot of crop residue remaining on the surface – to name a few. 

FYI: Attached are a few pictures of Goss’s Wilt infection.   
1. Younger corn plant showing leaf damage and signs of stalk infection when the young plant stalks were split open.

2. Stalk cut away showing healthy stalk on left and internal infection of stalks in different amounts.

3. Leaf infection lesions on a more mature corn plant.  Generally a syrupy or greasy appearance may also be visible for some time on or around the outer area of the Goss’s Wilt lesion.

4. Looking down the row at corn plants that have Goss’s Wilt lesions.

5. Another look at infected upper leaves on Goss’s infected plants.

Remember that Goss’s Wilt is a bacterial infection so application of a fungicide will have no real affect on the Goss’s Wilt pathogen or the prevention or reduction of it in a corn field.  At this time no hybrid from any company is 100% resistant to the Goss’s Wilt pathogen but some varieties show a lot more resistance than others when in the presence of the Goss’s Wilt pathogen.  In addition, testing is being done by Universities on some chemical products that claim to reduce Goss’s Wilt infections.  Ask your local Hoegemeyer District Sales Manager or Agronomist about hybrids that have good Goss’s Wilt tolerance for your acres.

Photo credits:  University of Nebraska & Iowa State University    
 

Now is the time of the year to take a good look at what is going on in your fields.  You may ask why look now as we are getting close to maturity and what has happened now can’t be reversed.  True, you may not be able to change what has happened up until now but this is the time to observe, evaluate and learn to see if you should do things differently next year.  It is easy to see where problem areas are now but go one step further and make an effort to mark or keep a record of these areas because it will look a whole lot different next spring when the crop is gone and you try to depend on your 5 or 6 month old memory. 

Some things to consider might be:

• Areas that have yellowed or places where the crop may be shorter or stunted.  These might be areas to do soil tests on or possibly areas that may have insect or nematode pressures.  It might be places where at this time of year you can still see where excess water stood for periods of time or maybe it’s compacted areas.  Take a shovel or probe along and check it out.
• Diseased areas that are seen now.  This is a good time to check it out and see whether it might be fungal infection like GLS in your corn or Sudden Death Syndrome in your soybeans or bacterial problems like Goss’s Wilt in corn. Record their locations and the solution might be planting varieties that have more tolerance to these problems or is it time to rotate to a different crop here next year or the plan might be using some available management practice here next year like a spray or chemigate application.
• Areas in a corn field that you may see silk clipping or pollination problems.  This might be an indication that root worm beetles may have been at work and you may need to consider crop rotation, using a triple stack corn or using some other preventative measures like an insecticide.  Do not forget to take into consideration the heat we had both day and night this summer in relation to pollination or pod development time.
• Areas of crop lodging or goose-necked corn.  Don’t jump to one conclusion, it might be one of many causes from corn root worm, soil compaction, planting too shallow, too high of a population for that particular variety, previous high winds or potential root rot going on.  The best answer at this time of the year is to go out and investigate.  Don’t forget to take your shovel and dig some roots.
• Areas showing poor plant health.  Now may be a good time to determine if it might be low fertility.  If so, plan on taking soil samples this fall.  Also consider possible disease pockets.  If needed, don’t hesitate to get a second opinion.
• Soybeans dying early in areas.  Walk out and check those spots and determine if it is caused by drought complications or potential disease problems like Sudden Death Syndrome, White Mold or insect pressures from a pest like aphids or another possibility is plain old soil compaction.
• Check those fields for weeds.  Walk out and see what weed pressures you have (if any).  Note the problem weeds in order to help you determine what herbicides would be best for you to use next year or if the one you used this year did not do the job you wanted it to.  You may want to consider herbicide rotation.
• Check your populations.  While the crop is still standing, this is a good time to see if you had the populations you were trying to attain or should have achieved for both corn and soybeans.  If you can, do this in all of your fields but especially do it in those fields that have different varieties planted in them.  In corn, pull back some husks and check out the ear fill.  Make the decision if you might be planting that particular hybrid type thicker, thinner or just right.  In both corn and soybeans make sure that the spacing is uniform and that there are not a lot of spacing gaps.  While you are in the soybeans don’t forget to check out the pods on the plants and the pod fill along with the number of nodes and branches and how they are distributed on the plants too.  Make sure that the planter is doing the job you want it to do.
• Check out trash patterns left in the field.  No-till or limited till farming has saved time and helped limit soil moisture loss as compared to conventional farming practices but it also needs to be monitored.  Be aware that residue is a good environment for disease pressures and document any potential disease problems you may see.  Also, trash is a good ground temperature insulator so note if you have plants in heavier trash areas that came up later due to the varying soil temperature areas at planting time causing them to have poorer pollination, smaller ears and weaker looking plants.  Check this out too, plant spacing gaps in heavier trash areas may be caused by poor seed to soil contact due to hair pinning the seed on top of field residue because the planter could not cut through the trash or if row cleaners were being used they may not have been positioned right to move the row residue away.
• When checking fields and making plans for next year, remember what things were like when you planted that particular field.  Do you see a difference in planting dates?  What were field conditions like when you planted that field?  Was the field planted during a warm time period or a cold spell?  Did the field get a heavy rain right after it was planted?  Did you have equipment problems when this field was planted?  Because it was getting late, were the field conditions too dry or too wet and the seed was mudded in?  Was fertility lost due to leaching?  What was the previous crop or field history? 
• When you are making observations now, don’t forget what happened during the growing season either.  Did the field have hail, high winds, heat, too hot of nights, or other problems that need to be considered?  Did it get frozen early or did you do something different in this field that you did not do in your other fields?
• Think about preventing resistance for next year.  We have a lot of good tools to use for crop yield and crop health protection.  No matter how great these tools are today, they can become useless in the future if we do manage them correctly.  The old adage that “death” and “taxes” are the only two absolutes in life needs to be amended with one more absolute and that is “resistance”.  Mother Nature has and always will provide insects, weeds and diseases the ability to adapt or become resistant to the best of our tools and the ability for pests and diseases to adapt is thrown into high gear if we do not manage them correctly.  For example, Iowa State recently documented that one companies root worm event now has areas in the corn belt where root worms have developed resistance to it.  This should be a warning to all of us that rotation of products (mode of action) needs to be practiced in order to preserve these tools.  Rotation prevention does not only mean crop technologies but it also includes things like herbicides, fungicides, and many of the technologies we take for granted today and may wish we had tomorrow if we do not follow good management and resistance prevention practices now.