The poisonous Parthenium grass is covering the agricultural lands in Gaya district of Bihar state in India.

It is definitely going to affect the productivity of the soil and agricultural growth.

by

Dr. Nitish Priyadarshi 

Above photographs shows how the poisonous Parthenium grass is covering the agricultural lands in Gaya district of Bihar state in India. It is definitely going to affect the productivity of the soil and agricultural growth.

Gaya is already under the water stress zone which affects the irrigation. Growth of these herbaceous plants  will increase the problem many fold.

Lack of awareness among the local people and government agencies had helped these plants to grow rapidly on the vast areas of the district.

It will not only affect the agricultural products but also the health of the local villagers with asthma, Allergic, Trinities Sinusitis, dermatitis (type of skin disease) especially among the childrens, Eczema, Allergic papules and all types of Allergic reactions.

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. It has been declared noxious in America, Australia, India and many other countries especially those having tropical climates.

A single plant can produce 10,000 to 15,000 viable seeds that occupy roadsides, tank bunds, fence lines, waste lands, agricultural fields etc.

If it intrudes into the agricultural domain productivity is definitely going to be adversely affected.

It squeezes grasslands and pastures, reducing the fodder supply. Scientists describe it as a "poisonous, allergic and aggressive weed posing a serious threat to human beings and livestock."

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. No species of the past   or the present century can ever match with this.  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.

From the day it was perceived as a menace, efforts are being made to control the weed by different  methods. But so far, no single method appears to be satisfactory, as each method suffers from one or more limitations, such as 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 and by creating competition that result in 'survival of  the fittest'.

In the recent past, this approach gained momentum to do away with unwanted plants. Experimentally, 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. Cassia can be encouraged either from wild source or by introducing it in targeted areas.

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.

There is need for people and residents' welfare associations to put their heads together and declare a war on parthenium weed so that further growth in the area  could be checked. This will go a long way in the interest of the poor sufferers of asthma and other allergy-related disorders.