GDD as a Management Tool

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GDD as a Management Tool

• Northwest Crop Clinics
• January 4-7
• Jochum Wiersma

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So much to do, so little time

• Larger Farms
• Smaller margins.
• To stay in this business you need to
• 1) Become lowest cost producer per bushel
  produced
• 2) Maximize the quantity and quality of your
  commodity
• 3) Maximize the impact of your inputs.
• No Room for Error

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Maximizing Inputs

• To maximize the impact of your inputs on your
  production you need to
• 1) Proper rotation and resistance management
• 2) Proper storage and handling
• 3) Proper calibration
• 4) Proper application
• 5) Proper timing, timing, and timing
• Timing

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Timing

• To time inputs correctly, requires you to scout
  your fields and determine the growth stage and
  quantify the presence of the biotic stresses.
• Now you know why those
• darn extension people keep
• nagging you about scouting

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Scouting

• Please check any of the following scouting
  methods you have used in the past
• 1) Check each field once a week
• 2) Check each field once a day (at 55 mph?)
• 3) Check each field after scheduling the
  applicator
• 4) Outsource the scouting
• 5) Dont check fields at all
• 6) Check fields if I have time left in the day.
• Are plants on a weekly schedule?

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Another Acronym

• OST (thats east in German)
• Optimizing Scouting Time
• 1) How many times do I actually scout my fields?
• 2) When are the most critical times for me to
  scout my fields?
• 3) Are there tools available to me that allow me
  to schedule my scouting activities in advance?

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Optimizing Scouting Time

• In wheat
• 1) Fifteen distinct crop growth stages
• 2) Five of these are critical, with regard to
  crop management
• - 2 leaf stage (stand count, weed ID)
• - 4 to 5 leaf stage (weed ID, insects, and
  fungi)
• - flag leaf emergence (insects, and fungi)
• - heading to flowering (insects, and fungi)
• - physiological maturity (pre-harvest
  management).

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Crop Development

• Germination

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Prediction Tools

• Are there methods available that model crop
  growth and development of spring wheat, such that
  you can calculate the growth stage based on an
  independent variable?
• Growing Degree Days
• 1) Uses air temperature to predict growth stage
• 2) Simple and accurate.

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Growing Degree Days

• GDD(TmaxTmin)/2 - Tbase
• In wheat
• Tbase equals 32oF
• Tmax equals maximum temperature for that day with
  upper limit of 70oF up to Haun 2.0 and upper
  limit of 95oF afterwards
• Tmin equals the minimum temperature for that day
  with a lower limit of 32oF.

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GDD and Crop Growth Stage

• Emergence - approx. 180 accumulated GDD
• Leaf - approx. 140 accumulated GDD per leaf
• ? 1500 accumulated GDD to reach heading.
• How can you use GDD information
• Ad hoc 1) Calculate your own
• Predictive 1) Dr. Ed Vaseys program
• 2) First Knowledge Project.

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First Knowledge Project

• Joint effort of Meridian Environmental
  Technologies (UNDs regional weather information
  center), United Spring Wheat Processors, and
  University of Minnesota
• Objectives
• 1) Provide field specific GGD information
• 2) Forecast accumulated GDD information up to ten
  days in advance
• 3) Calculate corresponding growth stage and
  create corresponding notices for scouting and
  management decisions.

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First Knowledge Project

• The GDD information, along with associated
  notices, are posted on a web page customized for
  each field
• Access to the information is restricted to the
  grower
• A warning about an approaching decision point is
  sent to the grower by e-mail, fax or pager three
  to five days in advance, as a reminder to check
  the fields website.

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Future Directions

• Continued testing with USWP member
• Eventually commercial roll-out expected
• Other crops can easily be added to the model.
• If you are interested in participating
• 1) Contact me
• 2) Contact Meridian or Leon Osborne at (701)
  787-6044.

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Questions