Invasive weeds threatening India’s biodiversity

BHUBANESWAR - Toxic weeds, which came along with wheat that India imported over the last few years, now pose a serious threat to its crops, people and livestock, says a scientist associated with the National Invasive Weeds Surveillance Programme.

“A large amount of toxic weeds landed in our country during wheat import in 2006-07. They were imported through sea ports located in non-wheat growing areas like Chennai, Tuticorin, Kochi and Mumbai. They spread to different non-wheat growing areas during transportation,” Sanjay Saha, senior scientist at the Central Rice Research Institute, Cuttack, told IANS.

These weeds rapidly invade new surroundings, “often replacing” the indigenous species and posing a serious threat to biodiversity, he said.

The most invasive weeds are ‘Chromolaena odorata’, ‘Lantana camera’, ‘Mimosa sp’ and ‘Mikania micrantha’ which are now rapidly occupying the forest and grasslands while ‘Parthenium hystorophorus’ is found in non-crop areas.

While ‘Eichornia crassipes’ is found in water bodies, ‘Phalaris minor’ and ‘Aventa fatua’ are causing severe losses to crop productivity.

The Indian government imported about 6.2 million tonnes of wheat from 10 countries between 2006 and 2007 for public distribution.

Five other most noxious weeds, which have been detected during quarantine inspections, are Giant Rag Weed, Spiny Burr Grass, Hound’s Tounge, Horse Nettle and European Field Pansy. These weeds not only affect crop productivity but also pose a serious health problem to people and livestock, ranging from diarrhoea and paralysis.

“The five noxious weeds were found mainly from the consignments that came from Australia and Russia. We don’t know whether these five species were exported mixing them with wheat intentionally. But traces of these weeds are now found in several places in the country, including Orissa,” said Saha.

Traces of the highly toxic Horse nettle, which was detected in the Niali area of Cuttack district last year, have been found in three more districts in the state. They have been found in the Ghasipura area of Keonjhar district, the Sadar area of Cuttack district and the Chandbali area of Bhadrak district.

“A quick response team of scientists has been sent to those areas to assess the situation,” said G.J.N. Rao, a senior CRRI scientist.

The surveillance programme is being conducted jointly by the CRRI, Cuttack, and the Orissa University of Agricultural Technology (OUAT) in nine districts of Orissa for early detection of these invasive weeds before the launch of an eradication programme.

A similar programme is on in 10 other states.

The CRRI has launched an awareness programme in several districts of the state. It has also announced awards to those who help in detecting these weeds.

“It can pose a serious challenge if not mixed in the early stage. We want to make people aware of the danger of the invasive weeds. We are giving a cash prize of Rs.1,000 to anyone who gives information for the first time in an area. Once detected, we can go for eradication by burning and use of pesticide,” said Saha.