It is not known how often stock and wildlife eat knapweed seed heads, but tests indicated that 11% of the seeds eaten by mule deer and 4% of the seeds eaten by sheep pass through their digestive systems, with a viability of up to 22%. Dead spotted knapweed stems generally remain erect during the winter unless crushed by heavy snow-pack. They tried biological controls, too, with bugs that eat knapweed — also to no avail. “Many brands of weed killer help control knapweed. It emerges in the spring to form spreading branches and produces light pink to lavender flowers which bloom from June to September. This could be other plants, animals, insects or diseases. The plant is native to Eurasia but was introduced to North America in the late 19th century. spotted knapweed is a perennial, new rosettes are also formed during the summer and spring from established root systems. It seems that thinner weeds, like spotted knapweed or diffuse knapweed are easier for them to learn how to eat. body weight PER DAY eaten over a 28-35 day period. Mixing is important. They usually graze them successfully the first day in pasture. Swallowing however, is unaffected. Cattle prefer grasses over spotted knapweed. The striking pink display of spotted knapweed, Centaurea stoebe ssp. Mammalian herbivores normally shun this plant because of the bitter foliage; but they will eat it if little else is available, as occasionally occurs in overgrazed pastures. The affected animal cannot bite-off and chew its food in a coordinated manner. It changes the Ph … However, survey respondents indicated that under certain conditions sheep and goats will graze Russian knapweed, especially when the plants are young and after the animals have grazing experience. 3)This is complex question but one the major reasons invasives proliferate is a lack of competition from a variety of organisms that occurred in their native habitat. Potential Effectiveness: Most of the literature indicates that livestock will not eat Russian knapweed because of its bitter taste. Spotted knapweed generates between 400 and 25,000 seeds per plant. 2-4 D, Curtain Crossbow, Milestone and Feeder are a few brands. 2) Not many animals will eat it although goats and sheep will eat it at certain stages of the knapweed's development. Using more is dangerous to animals and humans alike. Spotted knapweed grows 12 to 60 inches tall, is more erect and has more limited branching than diffuse knapweed. Spotted & Diffuse Knapweed Species Centaurea biebersteinii & Centaurea diffusa. This is where more is not better. Bushier weeds or plants with spines, like thistles, take a bit longer. Another July has come and gone, but not all of the fireworks are over. micranthos, is still going strong in rangelands and old fields and along highways and railroad grades across the country. The toxic dose of green Russian knapweed is 1.8-2.6 kg/100 kg. Russian knapweed (Rhaponticum repens, previously referred to as Acroptilon repens) is a bushy rhizomatous, deep-rooted perennial. Some of the seeds of Spotted Knapweed can pass through the digestive tracts of livestock and remain viable; thus, these animals may help to distribute the seeds. She turned to Robert Hanke, who prefers to take care of weeds with goats. Sheep and goats will eat more knapweed, especially when combined with other management tactics.