ARS | Publication request: Forage radish winter cover crop suppresses winter annual weeds in fall and before corn planting

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 2010
Publication Date: November 29, 2010
Citation: Lawley, Y., Weil, R., Teasdale, J.R. 2010. Forage radish winter cover crop suppresses winter annual weeds in fall and before corn planting. Agronomy Journal. 103:137-144.

Interpretive Summary: Forage radish is a new winter cover crop in the Mid-Atlantic region that provides several ecological services including capturing excess soil nitrate in fall and alleviating soil compaction through the biodrilling capacity of its large fleshy tap root. The objective of this project was to characterize weed suppression during and after a fall-planted forage radish cover crop and to quantify the subsequent effect on direct seeded corn. Forage radish did not reduce population or grain yield in subsequent corn crops. Forage radish provided complete suppression of winter annual weeds in the fall and early spring but the suppression did not persist into the subsequent cropping season. When forage radish cover crops were used in place of preplant burndown herbicide treatments to control weeds in early planted corn, some weeds were present at the time of corn emergence but corn yields were not reduced as long as emerged weeds were controlled with a postemergence herbicide. These results will provide new information to growers and extension personnel on the potential weed management value of forage radish used as a cover crop prior to early spring planted crops.

Technical Abstract: Forage radish (Raphanus sativus L. var. longipinnatus) is a new winter cover crop in the Mid-Atlantic region. The objective of this project was to characterize the repeatability, amount, and duration of weed suppression during and after a fall-planted forage radish cover crop and to quantify the subsequent effect on direct seeded corn (Zea mays L.). Forage radish cover crops were grown in ten site-years in the coastal plain of Maryland and were followed by a corn crop in seven of those site-years. Forage radish was compared to rye (Secale cereale L.), oat (Avena sativa L.), and no cover crop treatments. Early and typical corn planting dates along with contrasting herbicide management strategies were compared over four site-years. Forage radish produced 3.9 to 6.6 Mg ha-1 of shoot dry matter and 1.3 to 3.2 Mg ha-1 of fleshy root dry matter when planted before 1 September. Forage radish did not reduce population or grain yield in subsequent corn crops. Forage radish provided complete suppression of winter annual weeds in the fall and early spring but the suppression did not persist into the subsequent cropping season. When forage radish cover crops were used in place of preplant burndown herbicide treatments to control weeds in early planted corn, some weeds were present at the time of corn emergence but corn yields were not reduced as long as emerged weeds were controlled with a postemergence herbicide.