Parthenium Hysterophorus

This pernicious plant Parthenium hysterophorus, also known as Congress weed, Carrot weed, feverdew, white top, chandani, ramphal or garghas is an exotic plant of American origin found in Mexico, USA, Brazil and others in the American continents. The plant came to India in the 1950s and was first noticed in Nagaland also at the construction site of the Circuit House Annexe building, Dimapur in early 1980s. It is assumed that some of its seeds have entered Nagaland along with the construction materials of that building as it is known to be transported in soil and mud adhering to vehicles and equipments that moves from place to place. It is also spread by flowing water and wind as the seeds are small and light. It is very resistant to decay and can stay alive in dry and hot soil for over 2 years only to germinate when condition gets suitable. The plant is capable of flowering when one month old and remains in flower for 6 to 8 months.
Within 2 (two) years time, the weed was seen flourishing in other areas  in the vicinity of the Circuit House, Dimapur and the Government being alerted, entrusted the Department of Agriculture to eradicate it before it became a nuisance in the state. But alas, it is every where today! The saddest of all is that our people still don’t belief what they are told about the weed!

How harmful is it?
It contains a poisonous chemical called Parthenin which causes rhinitis, sinusitis and acute eczematous dermatitis in man which on continued exposure becomes chronic. It is reported that “up to 10% of people living in parthenium infested areas in India suffer from allergic rhinitis, sinusitis “(Tower and Subba Rao, 1992)
As for agriculture and farm lands in the tropic and sub-tropic regions parthenium grows so luxuriously that it outgrows, over powers and chokes crops. Ingestion of the weeds, which is very common, by cattle produces unacceptable taints in meat (Tudor et al 1982). Even the milk of the cattle were found to contain parthenin causing allergies. It is reported that in Central Queensland in Australia, due to the presence of the weed in pastures, the sale price of cattle were being discounted up to 30% and sale of grain to some South East Asian countries had been adversely affected.

Control measures:
The best is to up root the plant by hand before it flowers. If flowering, up rooting and burning is ideal. Cutting the stem does not help as new shoot sprouts from the stump in no time.
Crop rotation with Marigold in rainy season has being tried.  Allelopathic affect is achieved by planting Cassia sericea plant along side the weed as its roots have kaoline that accumulate in the soil and interfere with the weed.  Using insects and plant pathogens (rust) is in practice for a number of years now. Chemical herbicides such as simazine, alachlor, nitrofen etc before emergence and glyphosate and paraquat after emergence are also being used.
Finnally, composting the whole plant whereby allowing the seed to rot. This is done by shredding all parts of the weed, gathering them in layers and covering them with soil or mud for a few weeks. This exotic weed is now found even in the interior part of the state. The camp sites of the BRTF inadvertently form the primary site for its spread in most places. Can’t blame them if that happens, considering the nature their work.
 It is not too late to get it eradicated. And we must do it if we don’t want to lose our farm lands to it and suffer from perpetual allergies.

Note: Sufficient information on Parthenium are found in the Internet