Research from the University of Missouri shows that early emerging weeds compete with corn in its developmental stages for available nitrogen (N) — and usually win.

In the study, when grasses were allowed to grow to 12 inches tall, they accumulated 16 to 50 pounds of N per acre. When additional N was applied to corn at sidedress before weeds were controlled as a replacement for lost N, the weeds accumulated an additional 10 to 16 pounds of N per acre.

N loss to weeds that are not controlled early adds up. At a cost of 33 cents per pound, 15 to 25 pounds of N used by grass instead of corn results in a loss of $5 to $8 per acre of N.

N loss to weeds also lowers yields. If that early weed competition results in 10 to 15 fewer bushels of corn, growers could lose an additional $35 to $52.50 of net income if corn prices are $3.50/bu.

Since early emerging weeds rob corn of the nutrients needed for maximum yields, eliminating grasses and broadleaf weeds in either Roundup Ready® or conventional corn is essential.

Grasses and broadleaf weeds are a threat to corn that you can control. Protecting your N investment by controlling weeds with soil-applied herbicides is a good foundation for success.