Sunday, July 7, 2013

The No Win Scenario

The "no win scenario" is a famous line among Star Trek fans.  James T. Kirk did not believe that a no win scenario ever existed.  However, the good captain of the Enterprise never faced harvesting a wheat field badly infected with fusarium head blight.  Fusarium has infected most wheat fields in our area and the wheat harvest is not going to be any fun. Recent rains and humidity are adding to the problem by promoting growth of this disease with the associated higher DON levels that make elevator owners and farmers trade punches over the counter. Why is it such a problem?
Fusarium is a disease that flourishes under damp weather and moderate temperatures. It also is a disease that needs a very specific timing for infection.
Infection occurs at flowering time.  Wheat heads neither emerge nor flower all at the same time.  Main heads always emerge sooner than tiller heads.  Each head itself starts flowering at the base of the head and progresses to the top.  Without going into detail, fusarium spores explode in bursts and if the wheat flower is receptive to the spore, the spore will infect the flower and prevent the kernel from forming.  This timing of spores vs flower receptivity is very precise and is why only part of the head is infected. Temperature and humidity fluctuation from one day to the next can greatly change infection levels.  Sometimes the infection is at the bottom of the head, sometimes the middle, sometimes the top.  It is frustrating to know that it can't be totally prevented.
There is a temptation to believe the money spent on fusarium protection is wasted, but not so.  Fungicides contribute to reduced infection levels by protecting the flowers from infection.  However, the labels of both Prosaro and Caramba claim suppression, not complete control of fusarium head blight.  With heavy disease pressure there will be some infection.  Where no fungicide is used infection levels skyrocket and can result in a product that is practically unmarketable.  It literally can be classified as toxic waste. Fungicides definitely give us a fighting chance.
Economic losses from fusarium come from two directions.  Infected flowers do not produce a kernel or at best a light kernel.  The direct result is lower yield.  The bigger problem is with the right weather the infection moves within the stem of the head and spreads onto the skin of healthy kernels.  These stick out like a sore thumb in a grain sample and we can't keep them out of the sample.  The weather has been perfect from the fungus point of view.  That is where the no win scenario comes into play.
The standard recommendation from the agronomy crowd is to harvest early and pay the drying charges for one very good reason.  Grade discounts are higher than drying charges.  DON levels will rise every day the crop stands in the field.
Grizzled combine veterans have little patience for agronomists telling them when to go to the field.  Few agronomists have had to write the cheque for the extra fuel burnt while harvesting high moisture wheat.  Few agronomists have spent much time sitting on the edge of the seat in a combine cab hoping that the next wad of green straw going into the cylinder is not followed by complete silence.  Few agronomists have struggled with cylinder, concave and sieve adjustments necessary to separate wet kernels from tough straw and at the same time keeping lighter infected kernels from contaminating the sample. Some combines are just not capable thrashing tough wheat no matter how good the operator.  The ultimate no win scenario.  Regardless, harvesting as early as possible is still the best tactic against the no win scenario.
Can a pre-harvest glyphosate help dry the plant enough to make a difference in harvestability and reduction in DON levels? The short answer is yes, it will help.  If there is no clover under seeded or if you know your combine struggles badly in tough wheat, it will tip the odds of a clean  sample more in your favour.  Get some advice before you spray.  A good agronomist may not know a rasp bar from a top sieve, but he or she will know how to properly time the spray.  The wheat plant must be physiologically mature.
The 2013 wheat harvest will be a test of will.

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