Crofton Weed Ageratina adenophora (Sprengel)

The crofton weed, Ageratina adenophora(Sprengel), a plant native to central Mexico and Costa Rica, has invaded more than 30 countries and regions of tropical and subtropical zones. In the 1940s, it was introduced from Myanmar into the south Lincang (e.g. Cangyuan and Gengma) of Yunnan Province, China. Subsequently, this weedhas widely spread throughout Southwestern China including Yunnan, Guizhou, Sichuan, Guangxi, Xizang Provinces and Chongqing, with an ongoing spread eastward and northward at a speed of 20 km per year. The crofton weedhas caused serious economic losses to agriculture, forestry and livestock, and severely damaged the ecology and environment of China’s native habitats, e.g. exposure to or consumption of this weedmakes livestock sick. In addition, the crofton weedcan establish monoculturesin places where diverse native communities once flourished. Potential invasive mechanisms of this weedhave been investigated in China, e.g. biological characteristics responsible for its rapid spread, allelopathyon native plants, and effects on soil nutrition and biota. Moreover, we summarize and discuss possible control methods for the crofton weedin this chapter, including chemical control, biological control, replacement control, and comprehensive utilizing.