Leaf disease can strike anywhere on a corn plant, but where does it take the biggest bite out of corn yield?
In this Real Agriculture Corn School episode, OMAFRA plant pathologist Albert Tenuta explains that diseases such as northern corn leaf blight (NCLB) and grey leaf spot typically take root in field residue where pathogens overwinter and work their way up the plant during the growing season.
“Early on you’ll see the disease developing down low. Again that’s an indicator it’s either residue born or moving up the plant,” says Tenuta. “The middle of the plant is the key area that needs to be protected from a yield standpoint – the ear leaf and those just below and above the ear are key. This is where all the action is.” Maintaining the health of this ‘factory zone,’ as Tenuta calls it, is critical for growers to reduce the yield impact of disease.
In trials, Tenuta observes anywhere from 20 to 40 bushel per acre yield loss where infection starts at the bottom of the plant and moves up to the middle of the plant. He says disease has much less impact when it arrives later in the season.
“With northern corn leaf blight, you’ll start seeing it up at the top. By that time, when we start seeing lesions infecting the top two or three leaves it’s not really a big risk factor from a yield standpoint,” notes Tenuta.
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