July/August 2024 - 24

VEG CONNECTIONS
Adding cover crops
into integrated weed
management program
BY STEPHEN MEYERS AND JEANINE
ARANA, PURDUE UNIVERSITY
C
over crop adoption in the U.S. increased 17% from
2017 to 2022. While government incentives like those
through the USDA Environmental Quality Incentives
Program (EQIP) have encouraged this growth, the majority
of growers implementing cover cropping are motivated
by the role cover crops can play in improving soil health,
including increased soil water infiltration (Figure 1).
However, as weed scientists, we believe cover crops
can play an important role in weed management as well.
Here are four ways cover crops can be implemented
into vegetable production systems with the goal of weed
management. We realize that not all of these methods
will work where you farm, but we hope that you will
consider this a starting point.
Figure 2: Fall-planted cereal rye and crimson effectively
suppress winter annual weeds, including Italian ryegrass,
in a field in Pontotoc, MS. Photo by S.L. Meyers.
most common example from the Midwest is fall-planted
cereal rye that is roller-crimped for pumpkin production.
2. Between-crop " smother cropping "
Weeds thrive in bare soil and can take advantage
of the time between crops to emerge, grow, and set
seeds. You can fill this void with cover crops. We've
seen great success from buckwheat in this situation
(Figure 3). Under optimal conditions, it can grow quickly
and outcompete weeds. When it's time to plant the next
crop, it can be terminated with a burndown herbicide,
mowing, or tillage.
3. Between row weed management
In plasticulture production systems, weeds inFigure
1: A field of plasticulture strawberries after a
heavy rainfall event in Lafayette, IN. Cover cropped plots
(right) had greater water infiltration and less standing
water than bare ground plots (left). Photo by J. Arana.
1. Fall-planted cover crops
Fall planted-cover crops are typically planted after the
cash crop is removed from the field, although in some
instances growers will " fly on " cover crops into standing
cash crops with drones or agricultural aircraft. From a
weed management standpoint, this can serve a couple
purposes. Fall-planted cover crops can compete with and
suppress winter annual weeds. This has been an effective
way to manage multiple herbicide-resistant Italian ryegrass
(Figure 2) and occasionally glyphosate-resistant marestail.
Fall-planted cover crops can then be terminated in a
way that leaves the residue on the soil surface, providing
a physical barrier to weed emergence. The termination
method can vary by cover crop and cropping system. The
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between rows are often managed with cultivation and/or
herbicides. Cover crops can be used in these row
middles in place of herbicide. This works best for upright
crops that will not grow into the row middles. In the
case of our plasticulture-grown multi-year strawberry
research, a row middle cover crop not only competes
with weeds, but can also compete with and prevent
strawberry runners from establishing in the row middles.
This results in decreased hand-removal of strawberry
runners in this system.
4. Cover crops as a rotational crop
In 2022, we transitioned a portion of a neglected hay
field into vegetable production. After mowing, the field
was plowed, cultivated, and planted with buckwheat
for the summer. The buckwheat was mowed when it
flowered, and the field was intermittently cultivated until
early fall when a mix of vetch and cereal rye was planted.
The following summer, we terminated the cover crop
and planted vegetables. This provided an effective way
to manage perennial weeds and forages that would have
proved difficult to manage without this transition period.
July/August 2024

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