Colusa County
University of California
Colusa County



A few quick notes from Colusa-Sutter-Yuba

Mark Lundy

Wheat is in the ground. Now, where’s the rain?

Because the vast majority of our production occurs under irrigated conditions, California growers in the Sacramento Valley rarely get to experience the same level of anxiety about when and how much rain will fall as those in rain-fed growing regions.  One exception is the spring wheat that we grow over the winter rainy season.  We’ve had such little rain this fall that sprouting a stand in a timely fashion without irrigation would have been a challenge.  One wheat grower I’m working with in the S. Sacramento Valley planted in late October and is just now sprouting some wheat after the 0.3 - 0.5” that fell late last week.

Adaptive N management

While we don’t have control over when the rain comes, we do have control over how we react to it.  If the rain arrives on the wheat’s schedule and you have a crop heading for a big yield, it will have different N requirements than one heading for more a moderate yield if the rain doesn’t cooperate.  Splitting N applications in wheat is already a fairly common practice in the Sacramento Valley.  However, we might be able to improve on the precision (When? Whether? How much?) of our N splits and our overall N management if we can inform our in-season N application decisions by real-time information from the crop-soil system.  N fertilization is such a large proportional cost of wheat production, optimizing N management makes economic sense.  It also avoids environmental problems associated with over-application of N such as nitrate leaching.  Optimizing N applications are an economic-environmental win-win.

As a result, I’m starting some research across the valley this wheat season that will begin to develop some simple tools that growers and consultants might use in-season to manage their N in a way that adapts to how their particular crop is developing.  The more site-specific information we can gather from the crop and soil in a simple, low-cost manner, the more precise our management will become.  I’ll be reporting back on the progress of this research as we start figuring out what works and what doesn’t.  If there are tools or management approaches that you use and would like to share, please let me know!

High yield, high protein

The value of a wheat crop depends not only on its quantity but also on its quality.  As such, an important management objective for hard and durum wheat classes is simultaneously achieving both high yields and high protein.  Historically, there has been a tradeoff: a high-yielding crop will have less N available for translocation to the grain during the filling period (because it used it to build the yield components) than a lower-yielding crop, so high yield can mean low protein.  Wheat breeders are aware of this tradeoff and have been working (with some success! See below.) to minimize this tradeoff.  Aside from choosing a variety with the potential for high yields and high protein, late-season N applications (from booting to flowering) at around 40-50 lb N/acre have been broadly shown to boost grain protein content 0.5-1%.  Of course, there are times (eg. heading for a low yield or when the crop-soil system is N-saturated) when this application is a waste of time and money.  Late application of N to boost protein is one of the management decisions we are hoping to target with the in-field diagnostics mentioned above.

Evidence of progress?

The below is by no means a rigorous look at the question, but I did notice something interesting when looking for current varieties that have above-average potential in terms of yield and protein.  This first graph represents the ‘conventional wisdom’ about the yield protein tradeoff. It is based on data from a study conducted about 25 years ago in the Sacramento and San Joaquin Valleys.  Bottom line: higher yield = lower protein, the conventional wisdom.


The next graph is based on this past year’s wheat variety trials at UC-Davis.  Notice the difference in both the r2 and the slope.  It appears that the negative relationship between yield and protein is not nearly as strong as 25 years ago. Yet, there are several variables that could confound this conclusion.  Good work breeders?!


FYI: All information put out by the UC wheat breeding program and variety trials on a year-by-year and region-by-region basis can be found at: 


Previous Wheat Information:

Jerry Schmierer

Wheat Stripe Rust has become a big problem to growers in the Sacramento and San Joaquin vallies. The major difference this year is that the commonly used variety "Express" is only partially resistant to the new rust strains that have developed. The variety "Bonus" is very suseptible while the variety "Summit" is still resistant. The UC State wide variety testing program is very important in determining variety suseptibility to the new strains. We will have a more difinitive answer to this problem after havest in June. The

wheat stripe rust

Launch Image Gallery: wheat stripe rust           
shows symptoms and how different varieties react to the new strains of this disease.  To see what the varieties look like in the Colusa Variety trial, the

wheat variety trial

Launch Image Gallery: wheat variety trial                   
shows the differences in vaieties under field stripe rust conditions.


Wheat Variety Trials in Colusa County 2003

Research Reports:

More wheat information:

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