Corn Brace Roost: What Do They Tell Us?

corn field


The 2021 crop year has been quite variable. A dry winter/spring followed by periods of excess rain and dry hot weather has caused considerable plant stress. Corn plants typically give us many tell-tale signs of soil conditions. One current debate is about the purpose of corn brace roots. Corn brace roots help keep the plant upright and also help with nutrient, water, and gas exchange. Shallow planted corn utilizes brace roots to prevent the corn from lodging. So, brace roots are at least beneficial for maintaining corn yields. 

When corn with brace roots is dissected, however; a different story may emerge. Cut across the and stalk at the first leaf and then down through the center of the stalk to the root tip. Observe the lower part of the corn roots. Often the root tip up to the first brace root is brown and hard with few root hairs which is an unhealthy sign. Healthy corn plants without brace roots are typically white. The corn’s vascular system or plumbing for moving nutrients is clogged up. Often, several sets of brace roots can be observed on a corn plant, an indication that the vascular clogging is getting worse as the season progresses. The plant responds by sending out a new set of brace roots one node higher to bypass the clogged area.

A corn plant’s use of brace roots is quite variable depending upon the corn variety. Brace roots are not any different than regular roots. The brace roots form to transport water and nutrients into the corn plant. Corn roots exude sugars into the soil to feed the microbes in the rhizosphere or the area around a root. By feeding the microbes, the microbes release plant available nutrients for plant growth. When the plants vascular system or internal plumbing gets clogged, it develops brace roots to bypass the clogged area. Often the corn plant with brace roots is absorbing excess oxidized iron and sometimes too much aluminum. Vascular clogging can be associated with a lack of nutrition, toxicity (usually associated with excess use of herbicides), a lack of oxygen in saturated soils, excess nitrogen, and copper deficiency. Excess nitrogen and some herbicides tie up copper.

Adequate copper helps a plant remain flexible so it can bend in the wind without breaking. Copper is an essential nutrient needed to make lignin in the plant to provide structural support. Plants with adequate copper become less brittle, so leaves do not snap off easily. Copper is also vital for allowing plants fruit and grain to mature without cracking and splitting as moisture accumulates during fruit and grain fill. When corn is tasseling, you should be able to grip the stalk above the ear until the tassel touches the ground and do this without breaking off. Healthy corn is flexible and should be able to tolerate severe weather and high winds.

Are brace roots good or bad? First, in healthy soils, brace roots generally are not needed although there may be corn variety differences. However, brace roots are needed when the corn’s vascular plumbing gets clogged similar to heart bypass surgery. Sidewall compaction of the root zone due to wet conditions at planting, poor seed placement, and general soil compaction may restrict proper root development. During drought conditions, brace root may not grow due to a lack of moisture. Under dry conditions, brace roots may grow horizontally over the dry, hard soil surface. Cloddy soil conditions and planting corn shallow may result in a poor root system, known as “rootless corn syndrome".

Wet soil conditions early in the season may inhibit root development or cause shallow roots, preventing the plant from properly anchoring in the soil. Shallow root systems, especially in late planted corn fields, can be prone to potential drought stress and nutrient deficiencies that may result in root and/or stalk lodging. Brace root formation may not occur quickly enough under moist conditions to support the top growth of corn. Excessive moisture conditions can also cause incomplete brace root development that can lead to plant lodging. In saturated soils, high winds can easily cause plants to lodge by pulling out poorly anchored roots. Brace roots are often an indication that soils are not totally healthy or planting conditions were not ideal. Using proper soil health management, you may not see many brace roots, but your crop yields should be excellent!