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Effingham, IL | Assuming there has not been a post-emergent application of herbicide made to the field, I am relatively certain the symptoms shown in the pics is not herbicide related. The dark brown areas shown in the picture I would guess to be some type of disease which has infected the leaf. Which disease, I do not know but if you have access to a Distance Diagnostic Lab (most local county extension offices in Illinois offer this service) than I would take a sample to them for evaluation. More than likely they will not be able to give you a definitive answer on the spot but they will probably end up submitting the sample to the Plant Clinic at the University of Illinois. By doing it this way you will avoid the fees associated with submitting a sample to the Plant Clinic on your own.
As far as the bowing and the crinkled leaves are concerned I am relatively certain that it is a natural phenomenon I see fairly frequently at this stage of corn growth. The key here is the crinkled leaves AND the bowed stalk. Because both of these symptoms are appearing together tells me that the plant, at some point in time, was having problems unfurling its leaves as they emerged from the whorl. More often than not, this occurs during a period of extremely rapid growth of the corn plant. What happens is the plant grows so rapidly that it can not unfurl its leaves quick enough. This causes the stalk at the point where the leaves are not unfurling to elongate, thus causing the bowed effect you are witnessing.
Also, the crinkled leaves tell me that they were "stuck" together at one time. If you were to wrap your hand around the stalk just below the area where you see the crinkling of the leaves, then slide your hand upward along the stalk so that it draws all the leaves together you will see that the crinkled areas on each individual leaf occurs at the same point on the plant. Again, this tells me that those leaves were stuck together where the crinkling occurred. I would also expect that you can pick out these plants from a distance, probably from the field edge or even the road. The leaves of these plants are probably showing some yellowing while the surrounding plants are not. The reason for this is because the leaves which did not unfurl properly were not exposed to sunlight as quickly as the leaves of the plants that were unaffected, thus they are not as green as they normally would be. This will disappear rather quickly with time.
What does all this mean in the end? The bottom line is that I would not expect any ill effects from the bowing and crinkling. The affected plants will quickly outgrow these symptoms. I will however defer judgment on the brown lesions to the Plant Clinic. If this is indeed the start of some type of infection, it could have an impact on yield. Especially if the infection gets any worse. | |
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Corn problem, help identify.
