Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2007
Publication Date: 6/14/2007
Citation: Anderson, R.L. 2007. Crop sequence and no-till reduce seedling emergence of common sunflower in following years. Weed Technology. 21:355-358. Interpretive Summary: Producers in the western Corn Belt are interested in increasing the diversity of crops grown in the corn-soybean rotation. Our study found that adding cool-season crops such as winter wheat or canola reduces the number of wild sunflower seedlings that emerge in following years, compared with the conventional rotation. Apparently, the canopy of winter wheat and canola increase the natural loss of seed viability of wild sunflower, which reduces germination and emergence in later years. If this trend is consistent with other weed species, adding cool-season crops may help producers reduce the need for herbicides in their cropping systems.
Technical Abstract: Weed management is evolving to include cultural tactics that reduce weed populations. This study evaluated impact of crop sequence and tillage on seedling emergence of common sunflower across years. In the third and fourth year of the study, seedling density was sevenfold greater after two years of soybean with tillage compared with a two-year sequence of canola and winter wheat with no-till. Apparently, canola and winter wheat enhanced the natural decline of common sunflower seed density in soil, leading to fewer seedlings in following years. In the first year of the study, tillage increased seedling emergence of common sunflower compared with no-till; seedlings rarely emerged in canola or winter wheat. Most seedlings of common sunflower emerged in May, with more than 90% of seedlings emerging between May 7 and June 4. Cool-season crops grown with no-till may affect weed seed survival in soil in the western Corn Belt.