Across Nebraska, when scouting you may start to see more ears that have prematurely drooped. In corn, ears typically remain upright until after they have reached black layer (R6). Once corn reaches physiological maturity, the shank that supports the ear begins to deteriorate causing the ear to droop. However, many of our acres currently range in development from dough (R4) to dent (R5), with some fields just entering black layer (R6).
What is causing this phenomenon in our corn? And what does this mean for yield in those fields affected?
Conditions That Favor Early Ear Decline
There can be several contributing factors that cause early drooping of ears: drought stress, high temperatures, poor root development, population, and genetics can all be players. Note that if you are raising non Bt trait corn, then insect pressure from European corn borer could also be a possible factor for early ear droop on your acres. Root development and function could also play a role especially under drought conditions. One can also dig plants with droopy ears and examine root development to determine if compaction layers, etc. played a role in water uptake. Another thing Jenny has noticed on some plants with droopy ears is a darkened area of Fusarium crown rot in the lower crown area when splitting open plants that are dug.
This has been another interesting year weather-wise in Nebraska with the eastern portion of the state experiencing greater drought-stress than the western portion. We experienced early August rains followed by a lack of moisture thereafter. High temperatures with the lower humidity experienced in the afternoons can further reduce corn grain filling by increasing evapotranspiration, putting more stress on the corn plant. This was quite evident the past week with temperatures in the 90’s-100's causing plants to shut down. The past week of extreme heat coupled with moisture stress was too much for some plants to overcome. Even plants in irrigated fields are seen drooping after this week's heat and the inability for plants to keep up with the water demand. Thus, we feel drought stress coupled with the high heat are the biggest causes of ears dropping we're experiencing this year. The shank can become weakened due to a loss of turgidity in combination with carbohydrates being cannibalized under drought stress. Once the shank bends over, the pinch point restricts the flow of carbohydrates from the plant to the ear. If the flow is completely shut off, grain fill to the ear ceases and the kernels will prematurely reach black layer.
Source: unl.edu
Photo Credit: gettyimages-luc-pouliot
Categories: Nebraska, Crops, Corn