VietNamNet Bridge – The plant (Mimosa pigra L.), one of the world's worst invasive species, is developing rapidly in the Cuu Long (Mekong) Delta, but local authorities have not taken measures to thoroughly destroy the shrub.

The plant, also known as touch-me-not, originated in tropical America.

In the Mekong Delta, it has covered more than 6,000ha, flourishing along the banks of rivers and canals, on farming land, in vacant industrial parks as well as forests.

Scientists say that the plant first appeared in Viet Nam in 1984. It scatters its seeds through wind or water, can grow up to 6 metres long and has thorny trunks and branches.

It has had negative impacts on local fauna and flora and affected daily lives of residents, they add.

When the plant dies and decays, it releases a toxin called mimosin, a non-protein amino acid, that kills certain fauna and flora species.

In the Delta, the plant first appeared at the Tram Chim National Park in Dong Thap Province. It is said to have entered the park through irrigation systems that receive water from the Mekong River, said Nguyen Van Hung, the park's director.

From 10ha in 1980s, the plant now covers 2,000ha, accounting for 25 per cent of the park's total forest area. Of this, hundreds of hectares are covered densely with this plant.

Hung said his park has organised several slash and burn operations against the plant, but it has developed rapidly and encroached the living environment of indigenous flora and fauna species.

The park has planted some indigenous flora species like reeds and creeper species to restrict the spread of mimosa.

"We have done these things while waiting for scientists to find effective measures to destroy the plant," he said.

According to the Plant Protection Institute under the Ministry of Agriculture and Rural Development, there are three basic measures to destroy the mimosa plant –manual, chemical and biological.

The biological measure, which uses seed-eating termites and wood-eating worms, has been used in Australia and Thailand, said the institute, adding that Viet Nam is yet to do so.

Source: VNS