A review of all the literature by Osipitan et al. 2018 found that the more biomass a cover crop produces, the better the weed control will be. Small grains are the clear winner for both suppressing weed growth and generating biomass: barley, rye, triticale, wheat and oats are all good options. What is best for you comes down to seed availability and your rotation. If you grow wheat, planting barley, rye or triticale might not be a good idea, but using wheat as a cover crop can help. Using mixes is not recommended when weed control is the goal, as the various species will compete against each other.
The Weed Science Program at the Panhandle Research, Extension and Education Center has been working with cover crops for weed control since 2019. For all our field trials, we have used winter wheat, planted at 100 pounds an acre. A higher seeding rate might help with weed control, but it isn’t something we have investigated yet. With all the trials discussed below, the cover crop was terminated within three days of planting dry bean, through an application of glyphosate.
Study One: Winter Seeded Cover Crops Before Dry Bean In 2019-2021, winter wheat was seeded in October, and dry bean was planted in the last week of May. There were two treatments — those plots which had a cover crop and those that didn’t. For both treatments, the same herbicides were applied: glyphosate + Prowl® H20 + Outlook® applied pre-crop emergence (PRE), followed by Raptor® plus Basagran® at the third trifoliate. Palmer amaranth was not controlled where cover crops were not used, while season-long weed control was observed when a cover crop was planted (Figure 1).
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Categories: Nebraska, Crops, Wheat