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Title: EFFECTS OF TILLAGE AND LIGHT ENVIRONMENT ON EMERGENCE OF 13 ANNUAL WEEDS

Author
item Buhler, Douglas - Doug

Submitted to: Weed Technology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Weeds continue to plague farmers regardless of the crops they grow or the size of their operation. Farmers have become dependant on herbicides for weed control in most cropping systems. While herbicides are highly effective in most situations, they have been identified as contaminants of water and air and have led to the development of resistant weed populations. Farmers depend on herbicides in part because we have a poor understanding of weeds and there are few viable alternatives. About five years ago, German researchers reported that tilling soil at night greatly reduced weed populations compared with tilling during the daytime. Since weed populations and cropping practices in the central U.S. are much different from Germany, we set out to test night tillage under our weed and cropping conditions. With the aid of night vision scopes, we tested the effects of tillage during total darkness on the emergence of 13 weed species common to Midwest corn and soybean fields. We found that populations of certain weed species (small-seed broadleaf species) were reduced by up to 70% when tillage was conducted at night compared with the same tillage conducted during daylight. However, populations of other important weed species (annual grasses and large-seeded broadleaf species) were not affected by the timing of tillage. From this work we concluded that weed populations can be reduced by tilling the soil at night, but the size of the reduction was variable. Tilling at night is not a solution to all weed problems, but may help farmers control their weeds in some situations. This research is an example of how a basic understanding of plant biology can be useful in solving a real-world problem.

Technical Abstract: Seeds of many plant species require a brief exposure to light to induce germination. Modifying the light environment during soil tillage may alter weed emergence in agricultural systems. The objective of this research was to evaluate the effect of secondary tillage conducted during daylight and at night on the emergence of 13 summer annual weed species under constant soil and environmental conditions. Annual grass and large-seeded broadleaf species showed little response to light environment during tillage. However, weed emergence was often less when no secondary tillage was conducted compared with any tillage by light environment combination. Emergence of small-seeded broadleaf species was often reduced when tillage was conducted during darkness compared with tillage during the light. Reductions varied by experiment and species and ranged from 70% for common lambsquarters emergence to less than 30% reduction for Pennsylvania smartweed emergence. Large variations in response also occurred within species. Emergence of several other weed species was reduced when tillage was conducted in the dark. However, these reductions were inconsistent both among and within weed species.