The Secret to High Wheat Yields

Pat Boren
CPS Tangent

Last fall the Tangent Branch of CPS planted a wheat trial to achieve high yields using all the practices that we felt that would lead to the best yields possible.  Many of you attended the plot tour we hosted last spring to highlight this trial.  We tested two nitrogen rates, two growth regulators, and five varieties.  The plots were harvested with a small plot combine.  Our conclusion is that no one factor is the secret to high yields but that paying attention to the critical factors will lead to high yields overall.
Here is a summary of our results:

VARIETY              BUSHELS/AC        BUSHEL WEIGHT
TUBBS 06               173                                  61
GOETZE                 184                                   61
BADGER                 163                                  60.6
SOUNDER              122                                  60
WESTBRED            165                                  62.6

Many of the costs of raising wheat are constant (rent, equipment, seed, labor, overhead, etc).  It is essential that wheat yield well to be profitable.  The following are the factors that we considered in our wheat trial:
  • Site: Wheat needs well drained soil with PH in the 5.5-6 level with good Phosphorus and Potassium levels.
  • Variety: Goetze and Tubbs 06 are the two best yielding varieties for the Willamette Valley. Yamhill may do better in poorer drained areas.  There is some renewed interest in Madsen because of its rust resistance. Ever variety has its strengths and weakness.  Discuss your variety options with your CPS fieldman.
  • Nitrogen: The Mineralizable Nitrogen (Min-N) test has been working very well.  In our trial the Min-N test called for 90#N/ac.  In the plots where we applied 150#N/ac the yields improved only slightly.  The added yield did not pay for the additional nitrogen and protein levels increased to unacceptable levels.
  • Seeding Rate: OSU plots show 20-25 plants/sq ft is the best yielding rate.  Late plantings and no-till should be increased.  Where we harvested plots of double-drilled vs. single-drilled wheat (at 10” spacing), the single drilled wheat yielded better.   There is also a suggestion that very thick wheat makes the disease issues worse.
  • Lodging and Growth Regulators: Growth regulators did not increase or decrease yields in absence of lodging.  The plots that lodged showed lower yields as expected.  The growth regulators helped reduce lodging. Wheat in our trial and in OSU trials rarely lodged when nitrogen rates were based on the Min-N test.  Badger and Goetze are shorter varieties that resist lodging.
  • Diseases: Rust and Septoria are huge issues in wheat production in the Willamette Valley. The occurrence and severity will depend on the weather (wet, dry, cold wet early, late…) and variety.  A fungicide application at flag leaf should be a standard application.  Multiple spring applications can be beneficial when conditions are favorable for disease.  
    • The reality of disease control is that prevention and early treatment is better than trying to cure a problem.  Many times the decision to treat needs to be based on the judgment of the grower and fieldman based on what is happening in the field; weather, variety, yield potential, etc.  The fungicides available work well and utilize multiple mode of actions.  This year yields were reduced by up to 60% where plots were not treated with fungicides.  Our high yield trial was treated multiple times.
  • Weed Control: Everyone realizes that weed control is critical in wheat and for the following crop.  Wheat can be a good rotation crop if our chemical tools are utilized effectively.  Luckily we have a wide selection of herbicides; however there is not one program that works in all situations.  The particular herbicide to use and application timing depends on the weed spectrum in each field.   There is an increased occurrence of some weeds (Prickly Lettuce, Sow Thistle) that will need special consideration.
The Willamette Valley has great wheat yield potential.  Our non-irrigated ground can yield as high as any place in the world.  Many of the commodity crops have seen dramatic increases in yield potential over the last 10-15 years.  The quality of the growers, our soils, the varieties available, and weather make it very feasible to see big increases in the average wheat yields in the Willamette Valley. CPS will continue to test varieties and agronomic practices in 2011 to help in this progression.