Parthenium allergies

Parthenium or Congress grass is a poisonous, allergic and aggressive weed growing uncontrollably in wastelands, orchards, forestlands, flood plains, agricultural areas, urban areas, overgrazed pastures and along roadsides and railway tracks.

This plant is a native of the Americas. It has now spread across many nations creating a serious global biohazard. In India it was first sighted in Pune in 1956. It is believed to have been imported from the United States along with the wheat that was imported under PL480. By 1972 it had spread all over the country, from Kashmir in the north to Kerala in the south. Director Jay. G. Varshney, Director of the Jabalpur-based Directorate of Weed Science Research (DWSR) estimates that Parthenium has invaded 14.25 million hectares of farm land during 2001-07, seven-fold rise from two million hectares in 1991-2000. He considers Parthenium to be one of the world’s seven most devastating and hazardous weeds. It is probably the most dominant weed in Karnataka State where it infests about 5 million hectares.

Parthenium – Asthma – Precautions to avoid allergy.

Parthenium is prodigious in seed production – a large single plant produces up to 100,000 seeds in its lifecycle. As a result, approximately 340 million seeds can be present in the surface soil in one hectare of land infested with Parthenium. Seeds do not have a dormancy period and are capable of germinating anytime when moisture is available. The seeds are dispersed through water currents, animals and the movement of vehicles, machinery, livestock, grain, stock feed and other produce, and to a lesser extent by the wind. Most of the long distance spread is through vehicles, farm machinery and flooding.

In humans, Parthenium can cause allergy-type responses like hay fever, photo dermatitis, asthma, skin rashes, peeling skin, puffy eyes, swelling and itching of mouth & nose, constant cough, running nose and eczema. Exposure to Parthenium hysterophorous pollen extract leads to bronchospasm in stable patients of bronchial asthma. The parts of the plant responsible for the allergic responses are the pollen grains, airborne pieces of dried plant materials and roots of Parthenium. In the past, dermatitis was found in agricultural labourers but increasing numbers of city dwellers are being affected as the weed spreads into urban areas. In Bangalore, 42.5% of a large population sample showed a sensitivity to the pollen of the plant, contributing to an increase in rates of nasobronchial allergy (“allergenic rhinitis”). An aerobiological survey to study the incidence and concentration of the pollen of Parthenium hysterophorus in Bangalore for a period of one year reported that Parthenium pollen was present in the atmosphere in significant amounts either as single pollen grains or in the form of clumps during the months of June to August.

Parthenium – Asthma – Precautions to avoid allergy.

Humans are not the only species that are affected. The weed also causes dermatitis in animals like cows and goats. When they eat the weed, their milk produced by these animals takes on a bitter taste.

It is also a major threat to biodiversity as this weed quickly colonizes land, leaving very little space for other herbs and plants to grow.

Efforts are being made to control the weed by different methods. Uprooting manually is the finest option. However, it is important to ensure that the person handling the plant wear adequate personal protective attire like a gown, gloves and mask. An alternative option that does not result in significant exposure is mechanical removal using terraforming machines. The best time to conduct a manual or mechanical removal of the plant is during the rainy season. This is because the wet soil leads to ease of removal and concurrently, this happens to be a time in the lifecycle of the plant prior to the onset of flowering. During the last few years much emphasis has been laid on controlling parthenium through various biological agents like insects, pathogens etc.

At the personal level, the following common precautions assist in allergen avoidance:

1. Avoid going outdoors on days when pollen are present in high concentrations in air.
2. Close all windows in evening when pollen generally settles down to minimize their concentration.
3. Air conditioning decreases indoor pollen counts.
4. Take a bath after coming indoors and wear fresh clothes.
5. Eliminate Parthenium in your house garden.
6. Electronic/electrostatic precipitator can be installed