No-Tillers have long known that early season weeds often pose the greatest threat to corn yields, but one of the reasons why may surprise you.

As strange as it sounds, researchers at the University of Guelph in Canada say a critical factor in the yield equation may be the corn seedling’s ability to “see the competition.”

According to Clarence Swanton, chair of the department of plant sciences and one of the leading experts on weed control in corn and soybeans, research indicates that corn can sense the presence of nearby weeds through changes in light quality. As a result, the plant will change its growth pattern to be more competitive in the field.

Swanton’s research is based on a relatively simple phenomenon. As part of its natural defense mechanism, a corn plant will alter its growth cycle if it senses that competing weeds might shade it out. This forces the plant to use valuable energy to out-compete surrounding weeds by growing taller and faster — at the cost of your yield.

“The bottom line is that early weed control is key,” says Swanton. “The plant will react to changes in perceived light quality due to competitors, making the timing of weed emergence potentially more damaging to yield than the total number or types of weeds in the field.”

Based on the research findings, he says no-tillers should consider selecting a broad-spectrum pre-plant or pre-emergence herbicide program that stops early season weeds before they ever get started.

If a two-pass weed…