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Parthenium Hystrophorous
a poisonous plant
Scientists associated with the All India Co-ordinated Research Programme said
the rapid growth of the Parthenium Hysterophorus weed had become a threat to the environment and
biodiversity. It adversely affects the germination and growth of several crops.
The pollen grains of Parthenium Hysterophorus, or congress
grass 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. 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.
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Parthenium Hysterophorus plant |
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Parthenium
Plant
Parthenium weed's botanical name is Parthenium Hystrophorous. It is a herbaceous
plant, and a native of Tropical America. It is an annual herb and has a deep
taproot and erect stem, which becomes woody with age. Parthenium weed leaves are
deeply lobed. It is pale green in colour and has soft hair. Parthenium weed
flower is creamy white in color. The weed has a large number of stems. It has
small (1-2mm long) black seeds with white scales. They are not visible to the
naked eye.
History
The word Parthenium is derived from the Latin word 'parthenice', suggesting
medicinal uses. The origin of this obnoxious weed is traced to the Caribbean but
its adverse effects are felt largely in African, Australian and Asian countri.
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.
Parthenium entered India with imported foodgrains in the mid-1950s. "One of the world’s seven most devastating and hazardous weeds,
parthenium invaded 14.25 million hectares of farm land during 2001-07, compared to 2 million hectares in
1991-2000."
Parthenium has invaded 35 million hectares across the country including crop land, wasteland and forest areas, according to the
DWSR, which is preparing a report on this. Initially, the deadly weed occupied largely non-crop areas like wasteland, open forests and roadsides. Now it has now spread to cropping land at an alarming rate.
Parthenium
is Toxic
Parthenium has been declared noxious in America, Australia, India and many
other countries especially those having tropical climates. Scientists
describe it as a "poisonous, allergic and aggressive weed posing a serious
threat to human beings and livestock." It squeezes grasslands and pastures, reducing the fodder supply. |
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The presence of parthenium in cropped lands results in yield reduction up to 40
per cent. It is also responsible for bitter milk disease in livestock fed on
grass mixed with parthenium. Probing biological pollutant, highly successful in distribution.
The reasons for its fast spread are: (l) High germination ability throughout the year, (2) Large
seed production ability, (3) High survival rate, (4) Extreme adaptability in a
wide range of habitats. (5) Easy dispersal of seeds.
Problems associated with
Parthenium:
1. It is a vigorous species, which colonizes in grassy land . It grows rapidly
in bare areas along roadsides and water points.
2. It reduces the production of pasture.
3. It is very expensive to control.
4. It is a major health hazard to human beings.
5. It emits carbon dioxide and hence, poses a problem to nitrogen fixation and
becomes a parasite, dependent on standing crops and animals in its vicinity.
6. Its pollens are a major cause of asthma, especially in children and elderly
people.
7. It is a major cause of Allergic, Trinities Sinusitis, affecting about ten
percent of the people who live near it.
8. It is a major cause of dermatitis, a skin disease, among animals and human
being.
9. It reduces yield of milk and weight of animals.
10. It causes irritation to eyes.
Efforts to control the
weed
Efforts are being made to control the
weed by different methods. But so far, no single method appears to be
satisfactory due to high cost, impracticability, environmental safety, tem and Mechanical
Eradication. It is observed that cutting or slashing of parthenium enhances its regeneration. So
uprooting manually is the finest option. During the rainy season, the soil
remains wet and hence manual or mechanical removal can be done before the onset
of flowering with people's participation. This operation should be started
before blooming as uprooting after fruit setting will be a sheer waste of time
and money. As manual removal is not cost effective, it can be advocated only in
limited situations. If it becomes imperative to use labour, they should be
equipped with protective measures including ascertaining their parthenium
sensitiveness.
During the last few years much emphasis has been laid on controlling parthenium
through various biological agents like insects, pathogens etc . It was found that Cassia species can control parthenium.
C.sericea(C.uniflora), a non-nitrogen fixing leguminous herb, colonizes more
aggressively without giving scope for Parthenium to manifest. |
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Jabalpur-based Directorate of Weed Science Research (DWSR) Director Jay G Varshney
siad, "The proper management of parthenium weed could increase crop yield
by 30 per cent and help India achieve self-sufficiency in import-dependent food items like pulses and edible
oil." However, leading agri-scientist M S Swaminathan was surprised to learn that parthenium has spread to crop land as well. |
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