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The Yellow Iris

Over the past few weeks we have been struggling to track down the cause of many malfunctioning irrigation heads. The root of our problems has been traced back to seed pods from Yellow Irises. It appears the seeds of Yellow Irises have managed to find there way into the bottom of the irrigation pond and are subsequently pumped into the irrigation lines. The seeds then clog the screens completely blocking water flow or impeding the effectiveness of the irrigation system.

Course and Grounds staff are currently in the process of flushing and cleaning each and every irrigation head on the golf course. With over 800 irrigation heads on the golf course it is difficult to say how long this will be problematic for us. The irrigation heads may require to be flushed numerous times before seeds stop being pumped through the system.

Yellow Iris is a perennial aquatic plant native to Europe, Western Asia and North Africa. It was first introduced to North America in the 1800's as an ornamental plant for ponds and water gardens. The plant has since spread to many waterways, including those in parts of southern Ontario. Yellow Iris can grow in both treed and open wetlands, along river and lake edges, and on floodplains. The plant spreads by seeds and by underground stems known as rhizomes that send out new shoots above the ground and roots below. Yellow Iris is on Ontario's list of invading species and several American states have it listed as a noxious weed.

  • Yellow Iris can form dense stands with very thick mats of rhizomes and dead leaves that can displace native plants and change wetlands from a wet to a drier environment.

  • The plant reduces habitat available for wildlife, including native fish habitat and bird nesting and rearing sites.

  • The dense mats can block water flow in irrigation and flood control ditches.

  • Yellow iris is poisonous to both humans and animals if eaten, and its sap can cause dermatitis.

Further research is underway looking into alternative management strategies to eradicate this weed or at minimum, prevent it from being problematic to irrigation in the future. This may included trimming or hand picking seed pods. All other vegetation and plant material around the pond is considered beneficial to the ecosystem and wildlife of the pond, and care will be taken not to disrupt the natural system.

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