Decode early season corn growth.
Agronomy Bulletin 62 ─ Corn Development Stages
By properly identifying the various developmental stages in early season corn growth, producers can make well-informed decisions on replanting, applying herbicides, managing insects and more. Make sure to understand what to look for and how to differentiate the stages.
Factors to Consider
- Leaf blades
- Leaf growth
- Leaf collars
- <a href="http://agron-www.agron.iastate.edu/Courses/agron212/Calculations/GDD.htm" target="_blank">Growing degree-days</a>
- Select a staging system. Several different staging systems are used for corn development. Agronomy professionals use the leaf collar method, which is described in this bulletin. Others include the horizontal leaf method (also known as “droopy” leaf method), often used by the crop insurance industry and in the USDA Corn Loss Adjustment Standards Handbook, and the plant height method referred to on pesticide labels.
- Recognize emergence. Growth stages in the leaf collar method are separated into vegetative and reproductive phases. The first stage of vegetative growth is vegetative emergence (VE). This phase begins when coleoptiles emerge through the soil surface and continues until the first leaf collar is present.
- Identify leaf collars. Count the number of leaves with a visible collar, identified by the off-color band encircling the base of the leaf blade. The amount of collars corresponds to the vegetative stage for growth. Thus, a plant with four visible collars is in the V4 stage and so forth. The final vegetative phase, vegetative tassel (VT), is when all branches of the tassel are fully visible, extend outward and are no longer held in by the upper leaves.
- Determine stage when leaves are missing. Establishing growth stage can be complicated by the loss of lower leaves due to senesce, stalk expansion or weather-related causes such as frost or hail. When leaf loss occurs, the growth stage can be determined by splitting the stalk and identifying the stalk node to which the remaining leaves are attached. Each leaf originates from a node, with leaves one through four attached to nodes compressed at the base of the stalk, and looks similar to a downward-facing triangle. Leaf five is attached to the fifth node, separated from the fourth node by a very small (0.1- to 0.3-inch) internode. The internode between the fifth and sixth nodes is sometimes the first visible internode spacing later in the season. If the first observable internode is more than 0.4 inch, assume it to be between the fifth and sixth nodes. Once the stalk node that has a leaf with a visible collar attached to it has been identified, continue counting collared leaves to establish the V stage."
Identifying early season corn developmental stages is crucial for effective management. Accuracy leads to more timely and profitable decisions on the farm. For more information, contact your local Mycogen Seeds commercial agronomist or trusted agronomic adviser.
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