Alongside the springtime blossoming of our beautiful mountain flora are a number of noxious invasive plants which, if left unchecked, present significant threats to our ecosystem. Notable among these are the Canadian and Scotch thistles. Not to be confused with the dusty-looking Utah thistle, these are the ones with deep green leaves and bright purple flowers. Years of concerted efforts have greatly reduced the population of thistles in Round Valley, yet these are very hardy plants with seeds that persist for years. Eradication is a long-term project, so thanks to all who pitch in. However, it is common to see where well-intentioned people have pruned the flower tops of thistle plants while leaving the rest of the plant intact. This is counterproductive. This spurs the plant to quickly send up several new flower stalks in its place. It is arguably better to leave the plant alone than to just cut off the top. There is only one way to get rid of thistles: Kill the plants. This can be done in one of two ways. One is to pull the plant out by the roots. This is often fairly easy on larger thistles. Bring heavy gloves and clippers. Chop the plant up and leave it in situ. The second is to use a potent herbicide that is carefully applied to the plant, ideally before the flower heads appear. In either case, if flower heads are present, these need to be removed, put into a plastic bag, and deposited into the garbage. If the flowers are cut off and left on the ground, they can still use energy from the stem to produce viable seeds. So bring along a large garbage bag, heavy gloves and clippers. If you use a herbicide (necessary for smaller plants and large ones that cannot be pulled up), adjust the spray nozzle to emit a concentrated stream to avoid affecting non-target plants. Michael Tanksley Park City The post Thistle lesson appeared first on Park Record. ...read more read less