Home gardeners are well aware of the weed suppressive benefits of mulch. It turns out that farmers can inexpensively mulch a 200-acre soybean field too … by growing the mulch in place. That involves establishing a big hearty cover crop and then rolling it down so the dead leaves and stems act as a mulch.
Our Integrated Weed Management Specialist, Bryan Brown, participated in such a project with Cornell researchers Sarah Pethybridge, Matthew Ryan, and Julie Kikkert. They found excellent weed suppression by rolling a cereal rye cover crop into mulch prior to planting soybeans. Cover crops benefit soil health and, in this case, research showed a bonus of reduced incidence of white mold, a persistent soybean disease.
But would a cover crop mulch suppress our nasty new herbicide-resistant weeds? Bryan thinks so because these weeds tend to have tiny seeds which lack the stored energy needed to push through mulch. Through a New York Farm Viability Institute project that he leads, Bryan tested the suppressive effect of mulch on one of New York’s most problematic weeds, herbicide-resistant tall waterhemp. He found a control rate of 87%—good enough to avoid a yield loss on its own or be used in conjunction with alternative herbicides for even greater control.
It can be challenging for farmers to squeeze a cover crop into their rotation, so some are using a new practice to plant cover crops between rows of young corn, a year in advance of soybeans. This practice, called interseeding, allows the cover crop to grow rapidly when the corn is harvested. But some soil-applied herbicides used to regain control of herbicide-resistant weeds can injure the interseeded cover crops. So Bryan and project co-leaders Mike Hunter, Jeff Miller, Mike Stanyard, and Venancio Fernandez tested many of these soil-applied herbicides for cover crop injury and found several that are compatible. More good news for farmers who want to gain the benefits from cover crops while maintaining excellent control of herbicide-resistant weeds. As a result of this project, over 50 New York farmers have indicated intent to try this new practice.
Project Leader: Bryan Brown
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