Is vetiver grass planted in China an invasive alien species and becoming a weed?

We are often asked questions relating to whether vetiver is an invasive plant.  A recent study in China shows conclusively that it is not. Here is the abstract in English:
Abstract: The Vetiver Grass Technique (VGT) was introduced into China in 1988 via Mr. Richard Grimshaw, the Chairman of International Vetiver Network. It is an excellent eco-engineering and phytoremediation technology that has been utilized in multiple applications: soil and water conservation, environmental protection, habitat restoration, disaster and pollution control and so on. In the last two decades, VGT has been applied to over a dozen of provinces in southern China, and has made significantly ecological and social benefits. As a matter of fact, before it was introduced into China, “wild” vetiver had already existed in Hainan, Guangdong, Fujian for long, which can be traced back to 1936. However, there has not been conclusive evidence or information so far whether the vetiver was native to China or imported from abroad. At present, the only reproduction method of the cultivated vetiver around the globe is through asexual means (e.g., tillering), and vetiver sprawl and “repellent” phenomena haven’t been found in China. In contrast, vetiver can improve harsh habitat conditions and therefore benefits the growth of other native species, which leads to the shrinking or even disappearance of vetiver due to its poor tolerance to shade. In addition, vetiver is particularly sensitive to herbicides, and therefore, often can be completely annihilated by the spraying of herbicide. In conclusion, we think there is no scientific basis to conclude that vetiver is an alien invasive species and has potential to become a weed.
XIA Hanping1**, WANG Mingzhu2, XU Liyu2
(1-South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; 2- Nanjing Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China)