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Pretty yellow flower is noxious weed

by Weed Board Staff
| May 3, 2019 3:00 AM

As we talk about noxious weeds, one weed in particular stands out as a pretty yellow flower that you may see growing around lakes and other areas where water is present. This weed is called yellow flag iris (Iris pseudacorus), and as beautiful as it may seem, is listed as a noxious weed in Grant County. Though pretty, this plant can take over shorelines around lakes and can even grow so thick as to completely choke off water flow in narrow stream areas and irrigation ditches.

Yellow flag iris can regenerate from even a small piece of rhizome left in the soil, which means that tilling or digging can potentially spread the infestation further. Once yellow flag iris gets well established and takes over an area, it can be extremely difficult to completely eradicate. Complete eradication in a well-established site can take several years. Yellow flag iris is a perennial plant that is native to Eurasia, where harsh winters help to keep it in check somewhat.

Because yellow flag iris has such pretty flowers and is easy to cultivate, it is often sold as an ornamental to be planted along ponds and other water areas. Oftentimes, plants are even passed around by neighbors wanting to share what is thought of as just another pretty plant. This is why education on noxious weeds is so important. The more people know about noxious weeds the better. So far, we have discussed where this plant grows and why it can be so destructive, so how do we get rid of it? Read on to find out.

The best way to control yellow flag iris once well-established is with the use of herbicides. Since these plants grow close to water, it is best to contact the noxious weed control board if an infestation is found, as spraying herbicides close to water has the inherent danger of getting into the water.

If an infestation is found, contact the Noxious Weed Control Board of Grant County at (509) 754-2011, Ext. 4710. Visit our website at www.grantcountyweedboard.org for more information on noxious weeds of Grant County.