Canada Thistle
(Cirium arvense)
Introduction
Canada thistle (Cirium arvense) is an invasive, perennial species of noxious weed that spreads rapidly by both horizontal root shoots and seeds (Moore 1975). This species is native to North Africa and southeastern Europe. Canada thistle has been categorized as a noxious weed in forty-one states and occurs in most of the United States (Norland 2013). Managers of conservation land and property are legally obligated to control thistle which in many cases can be costly, can affect non-target species in multiple grassland settings, and requires continuous effort (Lym and Duncan 2005). In result, the infestation of Canada thistle on grasslands depreciates the value of property and also decreases the carrying capacity of livestock on …show more content…
2007). Canada thistle roots were collected for this experiment in March of 2005 and in September of 2005 from upland grassland in Wyoming. In the March of 2005 trials, two collections of weevils were kept on the foliage until rosettes were established, then 2-9 days after, the weevils were collected. In each experiment, the rates for 2,4-D and clopyralid were 0.98 and 0.28 kg ae/ha (Collier et al. 2007). The Montana trial herbicides were applied July 8, 2006 and for the Wyoming trials July 10, 2005 and July 15, 2006. After a 90 day, period the Canada thistle was then destructed for the drying and measurement of height, biomass and root