Arizona is Battling an Invasive Plant Species
Stinknet is a yellow "wildflower" that has taken over Phoenix and is moving south to Tucson
There are Burmese Pythons in the Everglades of Florida and Africanized bees are edging out local honeybees. Now Arizona is fighting an almost losing battle trying to keep “Stinknet”, an invasive species of plant, from taking over.
Although the plant has taken over the Phoenix area and some plants have been found in Tucson, it hasn’t taken hold yet in Pima County. There’s hope to keep this nuisance at bay.
What is “Stinknet”
Stinknet (Oncosiphon pululifer) also known as globe chamomile is a flowering plant in the daisy/sunflower family (Asteraceae) that is native to South Africa and Lesotho. It can grow up to two feet high during the winter, germinating from November to April. It flowers from February to June. The plant can be recognized by its fern or “carrot-like” leaves. When the foliage is crushed, it is said to smell like turpentine (hence the “stink” in its name).
Why is Stinknet a Threat?
Like most invasive species, Stinknet displaces native vegetation. The plant provides low nutrition value to animals who eat native foliage. When it takes over fields that cattle and other animals use as a food source, the animals don’t eat the Stinknet so they have less to eat. Exposure to the foliage causes severe dermal and respiratory allergic reactions to people. Dried patches of the plant are highly flammable, and the smoke is caustic.
These health and fire hazards have recently let the Arizona Department of Agriculture to declare it a noxious weed under Arizona laws. Legally, a noxious weed is any plant designated by a Federal, State or county government as injurious to public health, agriculture, recreation, wildlife or property.
How Did it Get Here??
Stinknet was first cropped up in Los Angeles and San Diego during the early 1980s, and it’s currently infested the counties in between those cities. It expanded its range to the Phoenix area during the early 2000s and can be found in Maricopa, Pinal, and Pima counties. Rapid spread in Maricopa County occurred due to above-average fall and winter precipitation in 2016, 2018, 2019 and 2020. Heavy infestations occurred in northern parts of Phoenix and Scottsdale as well as to the south along the Interstate 10 corridor towards Casa Grande. The first plant in Tucson was recorded in 2015.
What is an Invasive Species?
Invasive species are plants and animals that have been moved, typically over long distances, outside of their native habitat and into a new region, affecting other species that live there. "Invasive" does not refer to a species world-wide, but rather to particular populations of that species based on location.
Once the non-native species enter a new ecosystem, they can outcompete native organisms for resources like food, especially if they lack natural predators.
Humans are usually the main culprit (knowingly or unknowingly) in moving organisms large distances.
Damage Caused by Invasive Species
Invasive species have cost at least $1.4 trillion dollars globally in damages, which is approximately five percent of the world’s economy. In the United States invasive plants affect over 100 million acres of land each year.
Stinknet Closes Part of Casa Grande National Monument
The plant began to grow in the national monument’s picnic area, and therefore that portion of the monument will be closed from March 28 through April 30, 2024, according to their Facebook post and website. Visitors to the park are encouraged to be careful where they walk to avoid the spread of this plant nearby and, more importantly, around your home.
What Can Be Done to Prevent the Spread of Stinknet?
Remove Stinknet If You Spot It
If you encounter Stinknet on your property, remove it. If you pull it from when the ground is loose or wet from recent rains, you should be able to pull up the roots as well. Since this plant can resprout from the roots, try to get all of it. It can also be cut down but will regrow from the roots, so you’ll have to continually cut it back.
Remember to wear gloves and long sleeve shirts as the foliage can cause contact dermatitis. It can also cause allergies and asthma, so use caution (and perhaps a mask). Place any pulled plants directly into the trash to avoid the seeds being spread (bagging it and closing the bag is the best approach).
Most importantly, try to remove Stinknet before it releases its seeds. The earlier you remove it, the better, as sometimes removing dried plants can release the seeds.
Preventative Measures
If you are out hiking, camping or riding ATVs be aware of patches of Stinknet and avoid them if you can. If that is not practical, make sure you clean your shoes, change your clothing and make sure your pets are not carrying seeds on their fur.
Herbicides
I have found varying information online about herbicides used to battle Stinknet. The best advice I can give is for you to do your homework or contact a professional.
Participate in Citizen Science Programs to Remove Invasive Species
Maricopa County Desert Defenders have removal events that you can participate in. Dates of programs can be found here.
Next Time
Did you ever watch the popular series Longmire which ran from 2012 through 2017 on the A&E Network and later Netflix? The series is set in fictional Absaroka County, Wyoming but almost all of the filming was done in Northern New Mexico. On my most recent road trip I was able to visit some of Walt Longmire’s favorite places.
That's one terrible invasive_ far worse than the Scotch Broom we have here in western Oregon. LandDesk was reporting another invasive pest plant in the Four Corners area, cheatgrass. And I hope Poodle Dog Bush doesn't extend its range outside the Mojave! That's a real nasty customer!
I remember reading that about Casa Grande Nat'l Monument in the news recently. Good information, Jan, thanks! I haven't noticed it yet in the Flagstaff area, but will keep my eye out. Also good to know when hiking around the state.