Idaho Weed Awareness Campaign
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Curelyleaf pondweed                                

The Enemy - Curelyleaf pondweed (Potamogeton crispus) is a perennial aquatic weed that inhabits our Snake River as well as some small ponds. This is listed as Noxious Weed by the Idaho State Department of Agriculture (ISDA). The plant sprouts in the fall and can grow throughout the winter. It flowers in early spring and begins to break down during the summer, spreading vegetative buds called turions. The plant has curly leaf edges - like lasagna noodles – that are can grow up to 4 inches long. The stems are cream to red in color and generally do not branch. This plant produces rhizomes which allows it to seat deep into the soil as well as helps it spread by any soil (yes under the water) disturbance.

The Strategy - This plant spreads mostly by fragmentation, that is, any part of the plant can be gathered up in the boat, on the trailer, in the bilge waters, etc and can be moved wherever the boat is headed next. Once established it forms very dense mats and can cause boats to stall in the middle of the water system. Swimmers can get caught up in the thick mats and have extreme difficulty in swimming. As mentioned the plants die in the summer and this dead material can be hazardous to fish and other aquatic animals in the water, as well as keep the native aquatic vegetation from surviving.

The Defense - Prevention is key in controlling this plant. Make sure that all your equipment is free of any plant parts. Remember the key words – CLEAN – DRAIN-DRY. Make sure you clean your boat/equipment, drain all tanks, dry off the outside with a towel, mainly to re-inspect your craft. Mechanical removal of is very difficult due to the rhizomes that this plant produces. There are a few herbicides that the EPA and ISDA have approved for use in water, such as Navigate or Sonar, but the issue is not the threat to the fish or irrigation but due to the moving water will the herbicide stay on the plant long enough to properly control the weed. This plant does exist along the Snake River throughout eastern Idaho so if you need help we can properly identify the weed as well as recommend control measures

PLEASE NOTE -The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.

For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.

U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)

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