Parthenium is an extremely poisonous Weed. It has a deep taproot and erect stem, which becomes woody with age. This tropical annual Weed has attained the status of number one terrestrial Weed. In India approx. 40 million hectares of land is infested with Parthenium.
Its presence reduces pasture production. It is a major crop and pasture nuisance. It's a prolific producer of seeds and a single matured plant can produce up to 25000 seeds.
Parthenium Weed grows between the crops and if any type of poisonous insecticides is used to kill it the same will adversely affect the growing crops.
It not only consumes the fertility of the land but also affects the crop badly. Spreading of Parthenium Weed not only affects agricultural produce but also results in additional expenditure to control it.
Parthenium causes dermatitis in humans, and under continuous exposure it becomes chronic. Allergic contact dermatitis in man results from rupture of glands and deposition of parthenin and ambrosin on the exposed part of the body, particularly upper eyelids, sides of the neck, part of face, front of elbows and back of knees. It may spread to wrists, forearms and upper trunk.
It also results in loss of body hair. It spreads through nails, besides depressing the human nervous system.
This Weed is also a problem for livestock industry. Animals suffer from dermatitis, especially on face and ulceration in dental pad, tongue, and upper palate. Severe intestinal congestion and degenerative changes in liver and kidney is also observed. Consumption of large amount even kill the animals.
Animals get skin rashes on their udder and whole body. It is also responsible for acute illness, bitter milk and tainted meat when cattle's feed on grass mixed with Parthenium. The toxic effect on cattle is such that, a significant amount (i.e.10 to 15 per cent) of the Weed in the diet can kill the animals within 30 days.
The mechanical methods such as mowing and slashing result in rapid regeneration and spread of this Weed.
This has to be done carefully as the Weed causes skin and other health problems. Plants have to be removed before seeds develops, otherwise these seeds fall in the soil giving birth to thousands of new Parthenium Weed.
Immediate and concerted action is required to be taken to control or possibly eradicate the Parthenium Weed. If not, the control will become an enormous task in the future.
Biological : These include exotic insects. These are not effective because of the interference of weather. Long, dry day periods reduce the growth of the incests to very low levels making it ineffective.
Burning : This too has proved inadequate as it requires large quantity of fuel. Moreover, burning destroys all plants in vicinity and in addition creates air pollution.
Manual control : This involves pulling of the weed. This has proved fatal to the people involved as it causes severe skin diseases and other infections on contact with the weed. Matured seeds fall on the ground and increase infestation.
Herbicides : There are many herbicides available in the market. They destroy complete vegetation, it take 10 - 15 days to decay the vegetation.