Once known as tall whitetop, Nevada agricultural specialists are warning Carson Valley residents about the spread of perennial pepperweed.
Weed-free Forage Assistant Program Coordinator Jamie Greer said that during hay inspections in Carson Valley officials noticed more perennial pepperweed growing than in past years.
Greer said they are using the official name so people don't mistake other weeds for it.
"There's lots of weeds that have white tops," she said.
The perennial pepperweed is threatening to overwhelm native and agricultural plant species in the Valley.
"It appears to be invading Douglas County at an alarming rate," she said. "This threat is the noxious weed that has the potential to overcome native and agricultural plant species and overtake the beauty of the Carson Valley."
A single pepperweed plant can produce more than 10,000 seeds, which means that it spreads quickly.
It's typically found in waterways, ditch banks, wet meadows, pastures and disturbed alkaline soils.
It grows 2-6 feet tall and has lance-shaped green leaves. These leaves feel waxy, are toothed along the edges, and alternate up the stem of the plant.
The pepperweed is easily identified from the cluster of small white flowers that bloom at the top of the plant.
Usually it appears during June.
Greer said that Nevada law mandates all landowners and land managers control noxious weeds such as perennial pepperweed.
One of the most effective control method against pepperweed is the use of chemicals. Examples such as 2, 4-D formulations, metsulfuron (Escort), chlorsulfuron (Telar), and imazapyr (Plateau) are all chemicals that have proved successful in various locations and at various plant growth stages.
Mowing can be used to prevent the plant from going to seed, but it won't kill it. If the plant is already on the property, it may take several years to completely eradicate it.
The Douglas County Weed District and Carson Valley Conservation District are available to help. A presentation on the pepperweed is scheduled for Douglas County commissioners at their Thursday meeting.
