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ID Corn Growth Stage Before Applying Postemergence Herbicides

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Every year, corn yields are reduced because herbicides are sprayed after corn has exceeded critical growth stages. The most accurate way to stage corn is the leaf collar method. This method counts the leaf collars – where the leaf meets the stalk.

To determine corn leaf stages, count the leaves that have fully emerged from the whorl with the collar visible. Corn in the V2 stage will actually have 3 or 4 leaves visible, but 2 of the leaves will still be partially in the whorl with the collar not yet visible. Read herbicide labels carefully for height limitations. Some labels will use slightly different staging methods or will make recommendations based on plant height.

Did You Know

  • A new leaf will fully expand roughly every 3 to 4 days during early growth stages. Only about 2 days elapse in latter growth stages due to higher humidity and warmer temperatures.
  • A field is defined as being at a “given” growth state when more than 50% of the population shows the given leaf collar being counted.
  • The “plant height” method of staging growth will most oftentimes be between 1- to 2-leaf stages greater than the collar method, simply because several leaves are counted prior to a visible collar.
  • Prior to the V6 stage (collar method), the growing point is still below or just at the soil surface.