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Stalk rot in northwestern Iowa

MIDWEST: I want to talk a little bit about the development of stalk rot, which I’ve been noticing a lot of recently while traveling around Iowa.

Corn produces sugar through photosynthesis, which provides energy to the plant. The sugar moves to the growing points in the stalk and root during vegetative growth stages. After pollination, priority for sugar shifts to developing kernels. About 80 percent of the sugar demand for grain fill is met by photosynthesis, while the remaining 20 percent comes from storage in the stalk. Some of those sugars from the stalk are used for cell maintenance throughout the plant.

If stress reduces the corn’s photosynthetic capabilities, sugars will be taken from the stalk in order to fill the demand. If the plant does not produce sufficient sugar, stalks and roots will eventually become weakened, which then allows stalk rot organisms to invade earlier and break/plug up the tissue.

This only becomes an issue when your crop experiences stressors such as low moisture, high temperatures, extended cloudiness, low fertility or nutrient availability, corn rootworm feeding, hail, and leaf diseases. Some areas experienced several of these issues, which is why we’re starting to see stalk rot and even crown rot occur.

It’s recommended to go out and check at least 100 random plants in your field for stalk rot. Perform a pinch test at the bottom nodes and see if the stalk falls over. If 10 to 15 percent or more of your sample collapse after the pinch, consider harvesting that field earlier.

Reporting from Sioux Center, IA

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