Mosaic corn in your field? Don't fret just yet

May 20, 2020 1:54 PM
Blog Post

With the weather Iowa has recently experienced and the time of year it is, we all can expect to see purple and yellow corn and even some tattered leaves: the ugly ducklings of your field. Don’t fret just yet, cooler temperatures and wet conditions are all contributing factors to the mosaic colors of corn you might be seeing.

Corn with yellow coloration and purple leaf sheath due to cool, cloudy weather following emergenceAnother complication in addition to cool and wet weather is that some fields have corn plants in the 2nd to 4th leaf stage. This is the time frame where corn plants transition from the seminal root system to the rapidly developing nodal root system. Even with ideal weather conditions it is common to notice plant yellowing briefly during this transition.

Nitrogen and potassium deficiencies, herbicide injury, and soil compaction can all contribute to yellow leaf tissue, and the purple leaf tissue can be a symptom of phosphorus deficiency or problems that result in reduced plant sugar translocation within the plant. However, yellow and purple plants can also be attributed to cooler and wetter conditions that slow root and plant growth rates which in turn diminishes the ability of the plant to take up nutrients.

If you see the ugly ducklings in the field, this doesn’t necessarily mean there is a nitrogen, phosphorus, or potassium deficiency. Take the wait and see approach, and hope that warmer, drier weather prevails as you enjoy your Memorial Day weekend. As the temperatures and sunshine increase, it will promote root and plant growth rates and plant color will turn green once more.


Mark Licht Associate Professor

Dr. Mark Licht is an associate professor and extension cropping systems specialist with Iowa State University Extension and Outreach. His extension, research and teaching program is focused on how to holistically manage Iowa cropping systems to achieve productivity, profitability and en...