Posted: July 1, 2007, 12:00 a.m. PDT
Recent studies at Oregon State University found that birdseed mixes could be spreading weeds considered noxious or invasive species. During the work funded by the Agricultural Research Foundation at OSU, scientists scrutinized 10 brands of seed in retail stores, and the seed mixes contained more than 50 weed species. Every brand included weed seeds, and half of the brands contained six weed species.
Dr. Jed Colquhoun, associate professor at University of Wisconsin Madison, formerly with Oregon State University, said every weed seed can sprout, flower and spread after dropping from a feeder. "In fact, when we informally questioned landowners and farmers to investigate the spread of a relatively new weed in the Pacific Northwest -- velvetleaf (Abutilon theophrasti) -- we found it is growing in the soil beneath backyard bird feeders."
In less than a month, a weed seed might sprout beneath a birdfeeder. The OSU studies found that close to 30 species sprouted in 28 days.
The Weed Science Society of America — based in Lawrence, Kansas — suggests that birdwatchers take simple steps to keep nonnative plants from sprouting underneath the feeders in their yards.
Attach a tray beneath the feeder to keep seeds from reaching the ground. Consider augmenting seed feeders with foods that do not sprout, such as peanuts, peanut butter, raisins, suet cakes and mealworms. Read product labels on seed mixes to see if the manufacturer treated the seeds. Many manufacturers use guidelines from the U.S. Department of Agriculture and bake the mixes to kill weed seeds. Pull weeds beneath your birdfeeders before the plants flower and spread.
10 Invasive Weed Species
Buffalobur (Solanum rostratum Dunal)
Bull thistle (Cirsium vulgare)
Canada thistle (Cirsium arvense)
Common ragweed (Ambrosia artemisiifolia)
Dodder (Cuscuta spp.)
Field bindweed (Convolvulus arvensis)
Jointed goatgrass (Aegilops cylindrica)
Kochia (Kochia scoparia)
Puncturevine (Tribulus terrestris)
Velvetleaf (Abutilon theophrasti)