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Harrop: ’Tis the season to exterminate invasive holly

By Froma Harrop

Published: December 18, 2023, 6:01am

What could anyone have against holly? Plenty if you are an ecologist in the Pacific Northwest.

This cheery herald of Christmas, with its serrated green leaves and red berries, has become an invader, crowding out native plants on the forest floor. And the most fearsome of the 500 species is the beloved English holly.

Holly joins other beautiful non-indigenous plants now threatening less glamorous natives in the North American wilds. Purple Loosestrife, with its striking spikes of purple flowers, have taken over wetlands. Speaking of purple flowers, the South has Kudzu.

What makes the holly issue especially prickly is that, unlike Kudzu, it is commercially grown on farms. And so you have lively debate between those whose business is cultivating holly and those who want to kill it.

A cover story in High Country News — “A Festive Plant Runs Amok” — goes into the biological and sociological conflicts. It took a while for states and counties to label holly as a pest, but officially sanctioned holly hunters are now making war in the forests of Washington and Oregon. Holly cover in those states has about doubled in the last 10 years.

“We were looking for English holly, a cherished Christmas symbol that is threatening biodiversity in the Pacific Northwest,” writes Steven Hsieh, reporting from the battlefield. “We were there to poison it.”

County workers actually use .22 caliber shells filled with “a heavy concentration of tarry black imazapyr, an herbicide favored by weed technicians as the best — really, the only — method for tackling big holly efficiently.” These shells aren’t shot from a gun but rather hammered into the bark — in case you were wondering.

The more conventional tools are loppers, pruners, saws and trowels. One weapon, however, carries the terrifying name of The Extractigator. The Extractigator helps yank rooted vegetation from the earth.

Hsieh notes the difficulty of turning these bushes into the enemy. “The Reds and greens were unmistakably Christmassy,” he concedes. Holly is an essential ingredient in many Christmas wreaths. Homeowners in the Northwest shape holly into sharply neat hedges.

There are Holly Streets all over America, from Nashville to Pasadena. And there’s a Holly Society of America whose journal — walking lightly on the thorny topic — featured an article, “A Jewel or a Menace in the Pacific Northwest?”

Holly, without a doubt, is a ruthless multiplier. Dozens of suckers can emerge from a single root system. Where sagging branches brush the soil, roots for a new tree can take hold. If something cuts off a branch or a robin drops a berry, bingo, a new holly tree may be born. Scientists have seen suckers coming from dead trees nurture a live new plant. “Suckering from the dead,” is how one put it.

The ankle scraper thrives in the shade. A flammable tree, it can act as a ladder of fuel, carrying flames upward in forest fires.

The cultural attachment to holly and the economic interests in promoting it delayed Washington’s decision to officially cite holly as a threat to the ecosystem. The conflicting interests can certainly get messy. For example, the secretary of the Northwest Holly Growers Association also served on his county’s noxious weed board. Busy guy. It took a while, but the state department of natural resources now supervises holly-killing expeditions.

That’s all the bad news about holly we have for today. Be on notice, however, that the High Country News website has a piece on risks posed by pesticides used on Christmas trees. Headline: “What’s on your Christmas tree? Hint: Not just ornaments.

‘Tis the season to kill holly?” In parts of the Northwest, ‘tis always the season.

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