Corn Growth and Development

Grain Fill Stages in Corn

The corn crop is progressing through the grain fill stages of development. During this time, the corn plant switches nearly all of its resources to filling kernels. Plant health is critical during grain fill. Healthy leaf tissue, especially from the ear leaf up, is required for production of sugars via photosynthesis. Healthy roots intake water that is essential for sugar transport and cell expansion. Healthy stalk tissue is needed to transport sugar, water and nutrients and to structurally support the developing ear. Any stress that reduces the health of the roots, stalks, and leaves will negatively impact corn yield. These stresses include disease, moisture deficits, wind, hail, freezing temperatures and insects. The good news is that the farther the plant is along in the grain fill process, and the closer to harvest, the less impact stress will have on yield loss.  The following table lists details of the various grain fill stages, potential yield loss, and how stress impacts kernel development.

Much of the 2014 corn crop has experienced very favorable weather through pollination and early grain fill. If conditions remain favorable, we could see record yields across the Corn Belt. However, not all fields will be record breakers. In areas that have been short on rain in July and early August (Figure 1), one could expect ear tip dieback - the loss of kernels on the ear tip from kernel abortion or lack of kernel filling (Figure 2). Ear tip dieback can also occur in fields that have lost a large portion of leaf tissue above the ear from disease such as Goss’ wilt, Northern Leaf Blight, Rust, or Gray Leaf Spot. Greensnap and root lodging earlier in the year will limit top end yields in some fields. Late season nitrogen deficiency can be seen in some fields, which will limit yield potential. Record yields will also be tempered in fields that had poor stand establishment. A big component in the yield equation is ears per acre. The more ears that you have in a cooler than normal year with adequate rainfall, the higher the yield potential.

GDU Progress

The following table illustrates GDU progress from May 1 – August 7 for various geographies. We have fallen behind long term averages but are still ahead of 2009.

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