![]() Plants may have lost lower two leaves.Ĭollar of 9th leaf visible. Occurs approximately 45 days after emergence. Maximum row set by V8.Ĭollar of 8th leaf visible. The number of kernel rows being determined from V7 to V8. ![]() Root system extends approximately 18 inches.Ĭollar of 7th leaf visible. Permanent root system rather than the seminal roots is now the primary root system supporting the plant. Growing point and tassel above soil surface making the plant more vulnerable to a hail or freeze. Occurs approximately 3‐weeks after emergence. This is an important reference for crop growth staging.Ĭollar of 6th leaf visible. The first internode to elongate is approximately 0.5 inch long and is located just below the node to which leaf 5 is connected. However, flooding while the growing point is below ground can kill the plant, especially if temperatures are high. A hail or light freeze will cause little long‐term damage to the plant. Growing point is just below the ground surface. Leaf number and ear shoot formation is now complete. May have lost the coleoptile leaf by this time. Weed competition will begin to significantly reduce yield potential.Ĭollar of 5th leaf visible. The roots system is nor primarily nodal roots. Watch corn that is next to wheat or grass for Banks grass mites infesting lower surface of leaves. May apply 2,4‐D or dicamba from emergence through the 5th leaf stage without drop nozzles.īegin checking roots for Western corn rootworm larvae (white). Photosynthesis now very active and supporting the plant. The plants total leaf number and ear shoot are developing in the stalk. Occurs approximately 10 to 14 days after emergence. Plant is still relying primarily on seed reserves for survival.Ĭollar of 3rd leaf visible. ![]() If seed is planted too shallow the root system will have a difficult time becoming established.Ĭollar of the 2nd true leaf is visible. Permanent (nodal) root system will begin developing at this point. Seminal roots begin growing from the seed. ![]() Growing point of the plant should be 1 to 1.75 inches below the soil surface. This leaf will be shorter than later emerging leaves and has a rounded tip. Emergence(VE)Ĭoleoptile leaf (1st leaf) visible. Corn vegetative growth stages noted as “V” stages important for herbicide application timing. Image reflecting first leaf with round tip. The leaves in the whorl that are not fully expanded are not counted.įigure 2. Leaves are counted from the lowermost first (rounded-tip) leaf to the uppermost leaf with a leaf collar, which is the connection between the leaf blade and the leaf sheath. The vegetative stage are described using the leaf collar method (Table 1). In addition to the crop stage and condition, knowledge of the weed species and weed size are also important for effective post emergent herbicide applications. Non-labeled spray adjuvants can enhance herbicide injury from a post emergent application. For labels that provide both plant height and growth stage, the applicator should follow the more conservative recommendation. In stressful production environments with limited water or cool temperatures, corn growth is slowed, which results in magnified crop injury because the plant does not metabolize the herbicide quickly enough to avoid injury. Consequently, plant height does not always correspond to the correct vegetative stage so, it is important to accurately stage the corn crop prior to making post emergent herbicide applications. However, in high input environments with abundant irrigation and/or precipitation and fertility, internode distances can expand at a greater rate than new leaves. Some herbicide labels provide a recommended height for the last herbicide application as plant height often corresponds with a particular vegetative stage. For some herbicides, later applications can be made according to the label, but drop nozzles are recommended to prevent herbicides being sprayed in the whorl. ![]() Herbicide applications past the recommended application stages can result in significant crop injury. Post emergent corn herbicide labels define the latest growth stage for which herbicide applications can be made without causing crop injury. Post emergent herbicide applications are necessary for season long weed control. By Jourdan Bell, Texas A&M AgriLife Assistant Professor and Agronomist – Amarillo ![]()
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