Canada Thistle (Cirsium arvense) Response to Clipping and Seeding of Competitive Grasses

Abstract

Chemical restrictions, ecological concerns, liability issues, and public sentiment present challenges to land managers attempting to control highly invasive plants like Canada thistle (Cirsium arvense [L.] Scop.). Although herbicide application can be an effective control strategy, increasing limitations force managers of sensitive environments (e.g., national parks, wildlife refuges, protected water-bodies or waterways) to search for effective control alternatives.

Effects of Clipping an Invasive Plant Species on the Growth of Planted Plants of Two Co-Occurring Species in a Greenhouse Study

“…In our experiment, the biomass of S. canadensis could be reduced by up to 90% by clipping, indicating the high effectiveness. These results are consistent with those of Knudson et al (2012) and He et al (2018), who observed that clipping effectively inhibited the growth of some invasive exotic species [41,45]. The efficiency of clipping in reducing plant growth highly depends on the regrowth potential, which may be affected by plant size and the pool size of nutrient reserves stored in belowground parts [51][52][53].…”

“…Some greenhouse experiments have found that native species may help suppress exotic plants and favor the growth of desired native perennials [36][37][38]; however, these studies did not consider the priority effects of invasive exotic species [13,39,40]. Due to the presence of established invasive plants, native grass seeding alone could not inhibit the growth of invasive Cirsium arvense [41]. This suggests that whether planting native plants can significantly suppress the growth of invasive exotics may depend on the priority effects of the latter.…”

Competitive exclusion ofCirsium arvensein pasture: a simulated neighbour grazing-height experiment

“…By contrast, there were no mortalities or stunting in non-seeded plots implying that competition from the seeded herbs predisposed C. arvense to the effects of herbivory from the beetle (Bacher & Schwab 2000). Other field and pot experiments with biological control agents also reveal that interspecific competition reduces the performance of C. arvense (Ang et al 1994a,b;Ferrero-Serrano et al 2008;Knudson et al 2012).…”