Beware of This Noxious and Invasive Congress Weed

Beware of the common, noxious and invasive Congress weed species. The wild plant is not only a trouble to farmers, their crops and cultivation, but also to humans and animals. It has a scientific name Parthenium hysterophorus and belongs to Asteraceae family. The harmful congress weed plant has various English names like Santa-Maria, Santa Maria feverfew, Whitetop weed, and Famine weed. It is a common invasive species in countries like India, Australia, and parts of Africa. Some local names of the weed in India are Carrot grass (Gajar ghas in Hindi), Congress grass, Chatak chandam and Gandhi booti. Telugu names include Vayyari Bhama, Nakshatra gaddi, Mukkupullaku gaddi, Mukkupudaka mokka, Apadhi mokka, Sangedu mokka and Macherla kampa.

Picture of Congress weed (Parthenium hysterophorus)
Congress weed (Parthenium hysterophorus)

Origin of Invasive Congress Weed (Parthenium hysterophorus)

Parthenium hysterophorus was native to American tropics. Allegedly, it spread to India as contaminant with wheat shipments from the US in 1956 during Congress Party import in famine period. The weed spread like wildfire across India since 1970s and 1990s and has caused trouble to farmers especially, along with domestic animals and humans.

Parthenium Trouble to Farmers

Parthenium plant germinates exceedingly fast through its flowers and seeds, which can also spread through air. The Invasive Congress weed spreads and grows easily to invade disturbed land, including roadsides. Farmers often face disastrous loss of yield when Parthenium infests pastures and farmland (reason why it is called Famine Weed). The Parthenium weed produces Allelopathic chemicals that suppress the growth of crop and pasture plants. According to experts, the Parthenium weed can decrease crop yield by up to 40 per cent, causing trouble to agricultural farmers in India and other regions.

Picture: Congress weed (Parthenium hysterophorus) spread on a farm land
Congress weed (Parthenium hysterophorus) spread on a farm land

Harmful Effects on Humans and Animals

In some areas, heavy outbreaks of Congress weed have affected the livestock (domesticated animals raised in an agricultural setting) and human health. Apart from Allelopathic chemicals, Parthenium also causes allergens that affect humans and livestock, like that of frequent pollen allergies. Contact with the plant causes dermatitis in cattle and domestic animals, and dermatitis and respiratory malfunctioning in humans.

Control Parthenium

To control Congress weed (Parthenium hysterophorus), hand pulling is best solution. Root it out and burn after that. Some experts also suggest letting loose Parthenium-eating beetles. For instance, Zygogramma bicolorata, a beetle native to Mexico is found to be an effective control organism.

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