Noxious Weed Alert: Stinknet

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This plant stinks, in more ways than one

Pima County and the Regional Flood Control District (District) want to warn the public about the spread of a invasive and noxious weed species taking root in the community. Mishandling this plant can cause severe breathing problems that may require hospitalization.

Although humorously named, the stinknet plant is no joke to public health or the environment. Stinknet (Oncosiphon piluliferum) can cause severe skin and respiratory allergic reactions and when dry, stinknet burns easily.

Noxious Weed Alert--Stinket poster

Stinknet is a spring blooming annual weed that grows up to two feet in height and emits a pungent odor. It has unique bright yellow ball-shaped flowers. 

This plant has been spreading rapidly in both urban and wild areas around Tucson, especially in the Santa Cruz River areas of central Tucson. It has overtaken many areas in Phoenix, and can quickly dominate a landscape if not controlled.

We need to get ahead of this plant here in Tucson so we don’t end up with the situational nightmare afflicting parts of Phoenix, said Jonathan Horst, Director of Conservation and Research at the Tucson Audubon Society.

The dry spring this year has resulted in a modest appearance of stinknet in Tucson area, with plants restricted to low spots in neighborhoods and other properties, said John Scheuring, Conservation Director of the Arizona Native Plant Society

Plants are typically more common in low spots in neighborhoods and wash properties.

What to do if you come across this Noxious Weed Species

If you come across the plant, DO NOT: 

  • Mow the plant – This will not remove all of the roots and will leave seeds viable to germinate the following winter.
  • Burn the plant – This will increase the risk of wildfire and its highly caustic smoke creates a public health hazard.
  • Transplant or relocate the plant to other areas such as your home or different portions of the river.


  • Use herbicides to kill the plant if it has not yet flowered.
  • Pull and bag the plant, making sure to remove the root system from the ground.
  • Wear gloves when handling the plant to avoid a possible rash.
  • Notify the District when you see the plant (520-724-4600).
  • Map where you’ve seen it at

The District has been working with other local agencies to control the spread of stinknet around the Loop and in the rivers. 

Questions and comments about stinknet can be addressed to

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