Bird seed poses limited risk of spreading invasive weeds, says Canadian manufacturers

The spread of Palmer amaranth and waterhemp is a fearful situation when producers are increasingly dealing with highly competitive and often herbicide-resistant weeds.

This fear was felt a few months ago in Spokane, Washington, when a three-foot-tall Palmer amaranth plant was identified in the parking lot of a local Safeway grocery store. The invasive species was established and spread through bird seed, and identification of waterhemp followed a few months later.

Both are aggressive pigweeds, native to the U.S. Southeast and Midwest and capable of producing more than 100,000 seeds per plant.

Shaun Sharpe, a weed science researcher at Agriculture and Agri-Food Canada, suspects that the spread of the weed was likely from sunflower, millet and other bird feed ingredients from crops that were infested with the weed.

Typically, if seed isn’t high enough quality and cleanliness for human consumption, it’s moved to animal feed.

There aren’t any established populations of Palmer amaranth in Canada, but waterhemp has been found in Manitoba, Ontario and Quebec.

They can be distinguished from other pigweeds by their smooth, hairless stems.

Manitoba Crop Alliance notes the invasive weeds have been able to hybridize with other pigweed species, making identification challenging.

Canadian experience

Despite how common it is in the United States for bird seed to spread invasive weeds, the likelihood of it occurring in Canada appears low.

Most manufacturers of bird seed in Canada source their seed domestically, but those who don’t have to comply with Canadian Food Inspection Agency regulations. For bird seed to be imported to Canada, it’s required to be free from regulated weed seeds and pests, soil and plant debris.

Import requirements of the various components vary based on factors such as origin, destination, commodity and end use.

For example, nyjer seed is often sourced from Southeast Asia. Imported nyjer is required to be irradiated, a type of heat sterilization to eliminate possible germination.

Mark Bennett, owner of the Wild Bird Trading Company in Newmarket, Ont., uses a grain broker to purchase his seed from Western Canada. Before it gets to him, the seed is double cleaned and bagged.

“We ask them to remove all the immature seeds and the blanks … which are basically shells with nothing in them, that sort of thing. So, we get a good, high kernel content,” he said.

Once it arrives at Bennett’s facility, seed is further refined with sifting and vacuuming before mixing and packaging.

Armstrong Milling Co., one of the largest bird seed manufacturers in Canada, has the private-sector certification of being a Safe Quality Food mill. It said the facility is regularly inspected by CFIA to ensure non-native or invasive seed hasn’t been introduced to the feed.

“All of our suppliers are required to sign CFIA or Food and Drug Administration compliance agreements to ensure diligence and accountability throughout the supply chain,” Dan Murphy, one of Armstrong’s Safe Quality Food practitioners, wrote in an email to Glacier FarmMedia.

“And all ingredients undergo a triple-screening process to remove contaminants and ensure only the intended ingredient is used in production.”

However, control of weed seed is not just an issue for the manufacturers. Bennett said some of that responsibility rests with the farmer, who needs to control the weeds and ensure equipment isn’t contaminated.

Pigweeds such as Palmer amaranth and waterhemp are slow to emerge compared to other weeds like wild oats and kochia. If the weed is there, but small, the crop may out-compete it, says Sharpe.

However, it will jump on the opportunity to flower and go to seed, and that’s when it spreads.

“With these crops, there may not be as many options for a crop herbicide,” he said.

“Once the crop starts to establish, you want to scout and get an idea of, ‘do I have weird pig weeds coming up here, or is it fairly clean?’ ”

Removing any of the weeds before harvest is critical because hitting it with the combine will encourage spread.

Sharpe recommends spot management with fire or hand weeding, and contacting a weed inspector immediately if there is anything that looks like either of the invasive species.

Immediate action is key because these weeds can be very damaging.

The spread into agricultural land could affect yields and increase food costs alongside growth in herbicide resistance.

It could also spread in residential areas and wild areas, displacing native plants and contributing to loss of biodiversity.