Mile-a-minute weed, a fast-growing invasive vine native to India, Asia and the Philippines, can smother young plants and trees under its dense growth and poses a significant threat to nurseries, Christmas tree farms, reforestation projects and restoration areas. Photo courtesy of Maine Department of Agriculture, Conservation and Forestry

A fast-growing invasive vine called mile-a-minute weed has been discovered in Maine for what experts believe is the first time.

The Maine Department of Agriculture, Conservation and Forestry released a statement on Tuesday urging Mainers to be on the lookout for the barbed weed with triangular leaves in their gardens and other areas where infestation is common, such as nurseries, Christmas tree farms and reforestation sites.

A landowner in Boothbay Harbor found an outbreak of the weed among a batch of freshly installed landscape plants. According to Maine State Horticulturist Gary Fish, this is how the plant most often finds its way into ecosystems where it doesn’t belong.

“Mile-a-minute weed is a plant that we call a ‘horticultural hitchhiker,’” Fish said. “What happens is that sometimes it gets into root balls or pots of plants that are being sold. It also can show up in things like mulch. … But the most common way it’s moved around is in plants, and in this situation, we think that is what happened.”

While homeowners and gardeners might find mile-a-minute weed unsightly, the real threat it poses stretches far beyond its appearance. The plant’s formidable growth rate of up to 6 inches a day – or 25 feet in six to eight weeks – makes it constantly hungry for more room. This means the weed can destroy ecosystems by dominating them without giving native plants room to grow or providing ecosystem services to native animals and insects. It can also disrupt commercial agriculture by shading out crops.

Since the weed’s accidental introduction to the United States in the 1930s, several other states have been forced to aggressively confront it. According to the U.S. Department of Agriculture, researchers in West Virginia have started controlling outbreaks by using drones to drop biocontrol weevils over hard-to-reach patches.

Fish is optimistic that the state’s quick detection of the plant will make drastic measures like these unnecessary.

“We call this early detection and rapid response,” Fish said. “Hopefully, we’ve detected it early, and there aren’t a lot of these plants that have come into the state from other areas.”

Mile-a-minute weed is one of 33 plants on the DACF’s do-not-sell list. This means it’s crucial that plant vendors inspect their products before sale so that they don’t cause infestations on customers’ property, Fish said.

“(Plant vendors) need to be looking at whatever they import,” Fish said. “We’ve been training nurseries and other plant sellers for years to watch their pots, look for weeds that may be in the pot and make sure that (they) remove those before you sell a plant. Hopefully that helps to reduce that potential risk.”

The DACF asks people who think they might have spotted the weed to verify its identity, take pictures and email invasives.MNAP@maine.gov with information about its location.