Nitrogen Won’t “Fix” Yellowing Wheat that is Beginning to Appear

Yellowing wheat with a “spotty” field distribution. Photo: Colby Guffey, Clinton County ANR agent.

Carrie Knott, Grain Crops Agronomist-Princeton

There has been almost 19” of precipitation since Jan 1 this year. That is almost 6” more than the 30-year average. This is not only problematic for corn planting, but it has also resulted in a challenging growing environment for wheat.

In the last week or so, reports of yellowing (chlorotic) wheat that is either spotty or streaky in fields are increasing. Some have even reported yellowing occurring on side slopes. In many cases, producers want to know if this yellowing is due to nitrogen loss, given the extraordinarily wet spring, and if additional nitrogen could ‘fix’ the yellowing.

Yellowing wheat in a ‘streaky’ distribution in the field. Photo: Colby Guffey, Clinton County ANR agent.

In most cases, it is not likely that this yellowing is due to inadequate nitrogen. In most cases less than 10 lbs N/A are expected to be lost, given our weather conditions this spring. See the Nitrogen Management for the 2018 Wheat Crop blog for more information. Even for some fields that appear streaky, the streaking may be due to causes other than a missed nitrogen application. For instance, the streaking may be following the drainage pattern of the field, rather than areas with inadequate nitrogen.

This year, the wheat yellowing that is showing up is probably due to all the spring precipitation. For much of Kentucky, fields remained saturated for extended periods of time. The roots of wheat plants begin to die when soils remain saturated for extended periods and can also result in plant stress that yellows the plant.

At this point in the season, the soil has drained fairly well, but the yellowing is either remaining or just starting to appear. This is due to reduced root systems from saturated conditions earlier in the growing season. With reduced root systems, getting the water and nutrients needed to survive is a challenge, which is why the plants have remained and/or are beginning to yellow. If yellowing is observed, it will be important to dig plants to see if the root system is reduced before determining a course of action.

Unfortunately, there are no products that will ‘fix’ plants with reduced root systems. They simply need dry conditions with warm temperatures to grow new roots.

Wheat plant with greatly reduced root system. Photo: Brenda Kennedy, Plant Disease Diagnostic Laboratory, Princeton.