[Smart Farmers] Beware of the “grass bully”! Why do invasive weeds have the power to dominate?

The impact of biological invasions on global ecosystems is second only to ecological destruction, and they seriously threaten the stability of ecosystems, agricultural and forestry production, and human health in the invaded areas. The impact of invasive alien weeds on native plant communities has become a serious ecological problem. Invasive weeds replace native species, posing a serious threat to biodiversity and changing the structure and function of ecosystems.

Airplane grass profile

The scientific name of the airplane grass is the genus of the genus Vanilla, which is a perennial, tufted herb or subshrub of the Asteraceae family. Its rhizome is thick and the stem is upright, 1-3 meters high. All the stems are densely covered with yellow hairs or short soft hairs, easy to branch, and the branches are stretched, thick, and extend horizontally. The leaves are opposite, ovate, and have three veins. They have a pungent smell when crushed. The airplane grass is native to South America. It was once introduced to all parts of the world as a spice plant, fertilizer crop, and ornamental plant. It is now widely distributed in the Americas, Africa, and Asia. Today, the airplane grass has developed into a global malignant weed, posing a serious threat to the biodiversity, natural ecosystems, and social and economic development of the invaded areas. The airplane grass was first discovered in Yunnan, my country in 1934, and is now widely distributed in Guangdong, Guangxi, Hainan, and other places. In 2001, the International Union for Conservation of Nature listed it in the list of the 100 most threatening invasive species in the world for the first time. In 2003, sedge was included in the first list of invasive alien species in China jointly announced by the State Environmental Protection Administration and the Chinese Academy of Sciences, ranking 7th.

Airplane grass plant (picture from the Internet)

The morphology of airplane grass flowers (picture from the Internet)

The " bullying behavior " of airplane grass

As a malignant weed, airplane grass has strong sexual and asexual reproduction capabilities. Once a colony is established, it will rely on shading to block sunlight and hinder the growth of other plants; at the same time, it can secrete strong allelopathic substances, which have varying degrees of inhibitory effects on the growth and reproduction of surrounding organisms, affecting biodiversity. The invasion of airplane grass will also seriously interfere with the growth of economic tree species such as oil palm, coconut, citrus, cashew, teak and rubber. Studies have found that in agricultural land, the invasion of airplane grass will cause a 3%-11% reduction in grain production, a 4%-8% reduction in the production of economic forests such as mulberry leaves and pepper, and make banana plants in banana planting areas 1 meter shorter on average and lose 2-3 leaves. In addition, the leaves of airplane grass contain toxic compounds such as coumarins, which can cause skin inflammation and allergic diseases in humans. Ingestion of tender leaves can cause dizziness and vomiting, and ingestion by poultry, livestock and fish can also cause poisoning.

Airplane grass community in the woods (picture from the Internet)

Airplane grass in the sugarcane plantation (picture from the Internet)

How to prevent and control airplane grass?

Since the airplane grass invaded my country and caused harm, its prevention and control has become a research hotspot for government departments and relevant scientific researchers. Currently, physical control, chemical control, biological control, alternative control and other control methods have been formed.

Physical control: Where airplane grass is newly introduced or occurs in a small area, manual uprooting or eradication can be adopted; where it occurs in a large area, large mechanical equipment and other tools are required for manual removal.

Chemical control: Use pesticides to control airplane grass, such as cypermethrin, dicamba, triclopyr, etc. to remove airplane grass.

Biological control: In the areas where airplane grass has invaded, introduce some natural enemy insects for biological control, such as the sweet lily moth, the brown and black weevil, the gorgeous butterfly, etc.

Alternative control: Use the competitiveness of the survival of the fittest among organisms and use one or more plants with competitive advantages to inhibit the invasion and growth of weeds and reduce the potential harm of their spread. Using plants such as kudzu, red-flowered gray leaves and brachiaria can also prevent the spread of airplane grass.

Author: Luo Mingdan (graduate student of School of Life Sciences, Hubei University)

Scientific review: Xu Letian (Professor and doctoral supervisor at Hubei University)

Planning: Zhao Qingjian, Wu Yuetong

Editor: Lu Jingwen (internship)