Keep an eye out for this Russian
Nevada Appeal News Service
Don’t look now, but there’s another invasive plant proliferating around Carson City. No, not cheatgrass. We recently warned about that pest plant. The new (old) one is Russian knapweed.
“I first noticed Russian knapweed in Carson City about four or five years ago growing along North Carson Street near Glen Eagles restaurant,” said Ed Smith, who serves with the University of Nevada, Reno Cooperative Extension service.
“The purple flower caught my eye, it seemed out of place. It was just two plants at that time, and I pulled them out of the ground. I now see it distributed all over town from Kings Canyon to Saliman Road to Bully’s and even the planter in front of KFC.”
Never seen Russian knapweed? Take a look around. Or at the detention basin between McDonald’s and Bully’s restaurant.
The plant stands between 18 and 36 inches tall. It stands erect and has urn-shaped sepals holding the petals. The flowers on the tips of the sepals can be pink, lavender or white and are about a half-inch long. Shoots or stems are erect. Upper leaves are 3 to 4 inches long, shoots and leaves are covered with dense gray hairs. Upper leaves are smaller.
“Russian knapweed is a serious threat to Carson City’s open space and other undeveloped lands,” Smith said. Empty city lots are an open invitation to Russian knapweed and are often not cared for.
The knapweed is fatal to horses, so that puts it as a real crisis in horse-loving Nevada. It’s also known as Turestan thistle, creeping knapweed, mountain bluet, Russian cornflower and hardheads.
It’s native to the southern Ukraine, Iran, Kazakhstan and Mongolia. Russian knapweed was originally introduced to the United States in imported alfalfa seed brought from Turkestan near the turn of the century. Once imported, it was spread through domestically produced alfalfa containing Russian knapweed seeds. It grows on clay, sandy or rocky prairies, on saline soils – Nevada is a natural for the weed. Most Western states are infested with Russian knapweed.
It’s not an easy kill. For one thing, it is an “allelopthy” plant. Not in your vocabulary? It means that it exudes a chemical that can inhibit the growth of other plants. It gets into a disturbed area, kills off local plants and expands to an area of up to two square yards. That’s just one plant, expanding through its lateral roots.
And it can reproduce both from seeds and roots. That makes it hard to kill. Knapweed emerges in early spring, bolts from May to June and flowers into the summer. So it’s with us right now. And it thrives in land burned by wildfires.
Just mowing it down doesn’t do much good with those active root buds. And plowing up the plant cuts the roots into pieces, which can grow.
It regenerates through its root buds, so mowing just cuts off the tops. But it helps. Best technique is to “stress” the plant with herbicides and mowing, forcing it to use food stored in its root system and inhibiting growth. Just mowing or using a herbicide alone won’t do the trick.
Experts recommend combining the mowing stress with herbicides and also introducing hearty native grasses. When the knapweed dies the local plants move in. It takes time and repeated efforts to kill knapweed.
Here’s what Cooperative Extension recommends for homeowners:
Hand pulling, mowing and tilling may successfully control Russian knapweed. Herbicide requires vigilance and persistence. Establishing competitive vegetation is a must. The combination of methods increase in effectiveness as treatment is continued.
After spraying do not remove the dead plants until they wither or turn brown. And be sure to bring in good plants after treating the knapweed.
Some may contend that the Russian knapweed is a leftover from Cold War hostility. Forget it. The Russians suffer from the knapweed as much as we do.
• Contact reporter Sam Bauman at email@example.com or 881-1236.