Parthenium weed threat to biodiversity

ROURKELA: The rapid spread of the highly allergic and poisonous parthenium weed all over the country has alarmed scientists who described it as a major emerging threat to environment and biodiversity.

The pollen grains of Parthenium Hysterophorus, or carrot grass in common parlance, cause several diseases like eczema, asthma and dermatitis, a senior scientist of the Orissa University of Agriculture and Technology (OUAT), Bhubaneswar, Sudhansu Sekhar Mishra, said.

"It is a poisonous, allergic and aggressive weed whose pollens float in air and cause eczema, asthma, dermatitis, hay fever (kalazar) etc in human beings," Mishra said.

The weed was first sighted in Pune in 1956. It had travelled from the USA with wheat seeds and gradually spread to every corner of the country.

Scientists associated with the All India Co-ordinated Research Programme said the rapid growth of the weed had become a threat to the environment and biodiversity. It adversely affects the germination and growth of several crops.

Mishra said the pollens of the weed shed flowers of vegetables (tomato, chilli, brinjal) and inactivate nitrogen fixing bacteria in pulses due to secretion of a chemical substance (sesquiterpene lactones).

Not only human beings, the weed also causes dermatitis in animals like cows and goats. When they eat the weed, their milk becomes bitter and drinking it for some length of time may cause death.