Invasive Plants

Coping with an Alien Invasion

In an increasingly globalized world however, the extent and speed of species migration both have increased dramatically.

For the native plant world, they are real aliens – and dangerous at that. When plant species spread outside their natural habitat, they often become a serious threat. In new surroundings they frequently thrive better because there are fewer natural enemies or rivals. The spread of these invasive species is usually to the detriment of native plants. As a consequence, the local and regional biodiversity is seriously threatened.

Crop protection products can offer important help to control vegetation problems

In such circumstances, crop protection products can offer important help to protect the health of ecosystems. So, for example, Bayer CropScience offers special support to the U.S. Bureau of Land Management in its efforts to control the vegetation problem in public areas. Invasive plants that are easily combustible are widespread in these areas and thus pose a considerable risk, particularly during the summer. After fires, they are the plants that immediately grow back.

	Common ragweed at the stage of leaf development

Common ragweed (Ambrosia artemisiifolia) is a widespread invasive plant in Europe. Since 2005 Bayer CropScience has been helping French farmers in their fight against this weed and informed the public about the health hazard associated with it, such has asthma, allergies and eczema.

Invasive species are cited as one of the main causes for the reduction in biodiversity

A study published by the College of Agriculture and Life Sciences of Cornell University in New York shows how enormous the economic damage caused by these alien plant species really is. According to Cornell’s research, invasive plants result in a total cost of some 29 billion dollars per year in the U.S. due to harvest losses and control measures. Field weeds brought in from Europe now clearly outnumber native weeds. In fact, 73 percent of the field weeds are not native to North America.

The western corn rootworm (Diabrotica virgifera) originates from Central America, the botanical home of the corn plant. It migrated to the United States several decades ago, where it causes damage worth a billion dollars every year. To Europe it was probably introduced in the early 1990s with shipments of food destined for the U.S. army stationed in former Yugoslavia. Since then the western corn rootworm has gradually spread throughout the continent.

The speed at which such plants can spread when left unchecked is well illustrated by purple loosestrife (Lythrum salicaria), which was introduced to the U.S. from Europe as an ornamental plant. Every year it takes over an additional 115,000 hectares in the United States. Many wetland areas are now almost completely dominated by this plant. Its control alone costs the government 45 million dollars every year.

It is therefore with good reason that invasive species are cited as one of the main causes for the reduction in biodiversity in the Johannesburg Action Plan, adopted at the World Summit on Sustainable Development in 2002.

[ last update: Friday, June 6, 2008 ]