Down to earth, January 31, 2004 by Dipanjan Ghose, Centre of Advance Study, Dapt. Of Botany Kolkata University.

There are ways to weed Partheniun

Parthenium, a notorious weed, first sneaked into the country along with wheat grains imported from the US in the early 1950s. It has become a widespread menace ever since. The plant is a rapid colonizer and differs from other weeds in its remarkable adaptability to all kinds of soils and climatic conditions. During its initial years in India, Parthenium flowered between August-October in eastern India. However, its excellent adaptive qualities have ensured that today the plant completes its life cycle within a very short period & flowers 3-4 times in a year. Moreover, it can also proliferate vegetatively, if need be. Since, it is an exotic plant, Parthenium does not have natural enemies such as pests, pathogenic fungi, bacteria and viruses.

There is no room for any plant biodiversity in a Parthenium infested area. This plant causes diseases such as asthama, respiratory tract infection, rhinitis etc. But the luxuriant growth of this plant can be controlled by weedicides such as atrazine, metribuzin, monuron, neburon etc. Herbicides such as dicamba, glyphosphate and picloram have also yielded good results. Perhaps the common economical chemical control method is spraying brine salt (15% common salt) solution to dry out the plant. Plant extracts or leachates of marigold have also been found tom inhibit germination of Parthenium seeds. The introduction of the Mexican beetle (Zygogramma bicolorata) Satisfactorily curbed Parthenium growth in fields of central and southern America. However, this beetle feeds on other plants such as sunflower, xanthium and cockleur. But Parthenium is not always a menace. It has some potential uses as well: to make green manure or vermicompost, as an efficient binding agent to check soil erosion and as a raw material for biogaws generation. Parthenium pollen is also being generation. Parthenium pollen is also being used these days in the manufacture of pesticides.