Ohio State University researchers have found that nightcrawlers collect the seeds of giant ragweed and carry them into their burrows, a previously unknown behavior that explains why ragweed is such a pervasive weed.
Emilie Regnier, an Ohio State weed scientist, said that giant ragweed exhibits characteristics of poor success rate. Large seeds mean fewer produced per plant and difficulty becoming buried in soil to germinate; overall poor seed quality; high losses to mice; and low longevity in the soil, one to nine years, as compared to 20-100 years for some other weed seeds. Yet it’s one of the most stubborn weeds to control.
Nightcrawlers live most of their lives in permanent burrows, emerging at night to forage for organic debris that they drag inside the burrow where it decomposes and becomes digestible. Giant ragweed seeds have been found buried anywhere from near the surface to more than 20 centimeters deep. On one farm, the researchers estimated that nightcrawlers buried 70 percent of the seeds dispersed by giant ragweed.
(www.oardc.ohio-state.edu/story.php?id=3800)