With the low temperatures that producers experienced last weekend, there are concerns about freeze damage, low-temperature injury, and imbitional chilling.
Temperatures do not have to be below zero to cause concern for corn in the field.
In last week's Agronomy eUpdate from Kansas State University, Dr. Ignacio Ciampitti (Cropping System Specialist and my major professor/advisor) addressed the three previously mentioned forms of corn injury from low temperatures - all of which can be severe. READ THE ARTICLE HERE.
Low temperature injury occurs even at temperatures well above freezing - extended periods of 40 °F air temperature can cause damage to plant leaves. The severity of this injury after emergence is based on the condition of the growing point, which until vegetative stage V5-V6, is still underground. If the injury is only to the leaves and the growing point is not affected, the damage is cosmetic, and the plant should pull through fine. However, if a lengthwise slice to a plant reveals a brown or "water-soaked" base, the plants have likely been irreversibly damaged.
Low temperature damage example (Manhattan, KS)
After the periods of chilling experienced in the morning of both May 9 and May 10 (both of which consisted of extended periods under 40 °F), corn plants are now showing signs of minimal injury. See images below from our plots, taken on May 12.
The damage was identical on all plants across the field, which confirms an environmental stress. This injury is thankfully very light, with only some minor yellowing and small necrotic lesions on upper leaves. As suspected, a length-wise cross section of a plant revealed a safe and healthy growing point. This damage is strictly cosmetic.
If you're interested in checking hourly temperature patterns in your area, the Kansas Mesonet is a free resource available with stations around the state. Click here to check it out!
These cold temperatures are affecting corn development in other ways too. Stay tuned for more on Growing Degree Days!