All thistles are not bad, there is only one type of thistle that’s considered noxious enough for legal enforcement established in 2017 by Indiana Code 15-16-7-2…..…..Canada Thistle (Cirsium arvenseare) . This is one of five plants considered a noxious weed in 46 states including Indiana. Canada thistle is a non-native invasive species from Europe, and landowners with Canada thistle on their property are obligated to take measures to control it, therefore SSF controls this one type of thistle using various methods. Other thistles are often tolerated until they begin demonstrating invasive-like growth habits.
Unfortunately the traditional, agriculturally-rooted thought is that all thistle is “ugly” in fields and should be eradicated. This may be due to cows & horses avoiding the plant during grazing . Contrary to commonly held belief, all thistle is not bad, especially when viewed from a conservation perspective.
Benefits of thistles……
Thistles begin bloom phases during September – October and provide various forms of declining pollinator species late season blooms (nectar). Considering that during the last 20 years the population of Monarch butterflies have declined nearly 90%, some thistle should be tolerated. Especially field thistle (Crisium discolor), the leaves of field thistle are the only food for painted lady butterfly caterpillars.