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Title: TILLAGE IN THE DARK AND EMERGENCE OF ANNUAL WEEDS

Author
item Buhler, Douglas - Doug

Submitted to: Integrated Crop Management Newsletter
Publication Type: Popular Publication
Publication Acceptance Date: 2/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: There have been several recent reports in the media that tillage during darkness reduces weed populations. Unfortunately, some of these reports have oversimplified the matter. It is true that there are strong indications that tillage in the absence of light reduces the emergence of some annual weed species. The light requirement for germination found in many small seeded species is believed to be an evolutionary strategy for survival. Light sensitive seed buried deep in the soil remain dormant until soil disturbance, such as tillage, exposes them to light. It is extremely important to point out that research in Iowa and Minnesota indicates a wide range of responses to tillage in darkness among important annual weed species. It should also be noted that total darkness is required for a response to occur. Emergence of the annual grass species (barnyardgrass, green foxtail, giant foxtail, and yellow foxtail) was not affected by the time of tillage. Emergence of large-seeded broadleaf species (common cocklebur, giant ragweed, and velvetleaf) was also similar following tillage in the light or dark. Emergence of small-seeded broadleaf species (common lambsquarters, common ragweed, eastern black nightshade, pigweed species, Pennsylvania smartweed, and wild mustard) was affected by the time of secondary tillage. Emergence reduction with small-seeded broadleaf species ranged from 30 to 70%. Based on the results of this experiment and research conducted at other sites in the U.S. and Europe, it appears tillage in the dark may have potential as a component of integrated weed management. It may also be possible to design equipment that excludes light from the soil while working during daylight.