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| Integrated Management of Parthenium (Congress grass) Weed | | | Dr. Banarsi Lal and Dr. Pawan Sharma | 8/18/2018 11:01:53 PM |
| Parthenium hysterophorus commonly called as congress grass is an alien weed of national significance. It is also called as gajar ghas, white cap or top, gajari, chatak chandani, nakshtra gida, safed topi, asadi etc. Parthenium is most commonly called as carrot weed or 'gajar ghas' because its leaves look like carrot leaves. . It has been branded as "Cosmopolitan weed", "National culprit" and "National health hazard" due to its serious environmental threats. It is a menace to human beings, animals, farmlands, environment and biodiversity. It is a poisonous, pernicious, problematic, allergic and aggressive weed posing a serious threat to human beings and livestock. Initially it was a problem of barren and waste land but now it has become a chronic problem in the crops fields, orchards, forests, roadsides, railway tracks etc. It is a herbaceous, erect, annual plant belonging to subfamily Heliantheae and family Asteraceae (Compositae).It rapidly matures and can grow upto a height of 1.5-2.0 meter having branches and leaves covered with fine hair. It is a deadly weed infesting cropped and non-cropped areas. This weed rapidly covers the new surroundings and now it has become serious threat to our crops, environment and biodiversity. This weed has been fastly spreading like a wild fire and its invasion has been estimated to be about 35 million hectares in India. It is a nuisance in public areas like parks, residential colonies, road sides, vacant lands etc. It also blocks our many paths and reduces the aesthetic values of our parks, homes, gardens etc.
The origin of Parthenium is considered to be Mexico. In India, its occurrence was firstly noticed in Pune (Maharashtra) in 1955 and now it has spread across the nation. It mainly spreads through seeds. It is supposed to be introduced in India from the United States of America along with wheat and other cereals import. In India it has been noticed from Kargil region of Jammu and Kashmir to Port Blair in Andeman and Nicobar. It has been observed that this weed has reduced crop yields and has also affected environment and biodiversity of the nation. It can be seen on roadside, railway tracts, vacant lands, wastelands, agricultural, horticultural and plantation crops, industrial areas, irrigation canals etc. It is considered as one of the most problematic weed for all of us and has a wide adaptability to climate and soil conditions. It grows luxuriantly and does not allow any other vegetation nearby or underneath. It grows even in the Central Himalayan Mountains at an elevation of about 2000m above MSL. It has also been found to occupy large area of pasture land and hence reducing the fodder availability to animals.It has small white flowers and seeds of light weight which are easily dispersed to the distant areas by wind, water or through various human activities. It can grow up to 1.5 to 2.0 meter height and the average plant population is 112-828 per square meter. A single healthy plant can produce about 5000-25000 seeds. The weed has the potential of producing as high as 1, 54,000 seeds/sq. m. Its plants density varies from 25-70 plants/sq. m. Its seed viability has been observed up to six years or even longer than in the soil and more than 50 percent seeds remain viable for more than two years after their shedding in the soil. It has shorter life cycle of 3-4 months depending upon climatic conditions and it has the ability to grow throughout the year in one or other vegetative or reproductive phases but maximum growth occurs during monsoon season. This plant has the capacity to re-grow from the cut or broken parts.It lacks natural enemies like insects and diseases and it has allelopathic effects which are the majors factors responsible for its rapid growth.
In India and Australia it is considered as one of the greatest sources of dermatitis, asthma, nasal-dermal and nasal-bronchial types of diseases. Any part of the plant (even root) can cause the subsequent risk of allergic reactions (dermatitis). In humans it causes health hazards like skin allergy (dermatitis), hay fever, asthma and bronchitis with flowers, seeds and even hair on leaves. Allergic papules are observed in school boys when they volunteered for uprooting parthenium. It is toxic for animals and are equally prone to the harmful effect of this obnoxious weed. In dry season, when the animals do not get palatable species in grazing lands, they are forced to feed on parthenium. As a result milk taste becomes bitter and they suffer with ulcers in mouth and intestine. Whenever animals walk or graze through parthenium, their udders are inflamed and they suffer with fever and rashes. Histopathology of the kidney and liver revealed degenerative changes and necrosis. The milk consumption of the animals grazing around parthenium invaded fields is hazardous to man. Some animals feeding the parthenium are died due to acute dysentery, itching, cryhematous, development of oedema around eyelids, dorsum of tongue, loss of hair etc.Parthenium infests every type of agricultural crop, forests, orchards etc. and it drastically reduces the crops productivity.
Parthenin is the chief chemical (0.3%) found in the weed. The presence of sesqueterpene lactones such as Parthenin and coronopilin widely found in parthenium leaves cause diseases like dermatitis and rhinitis to humans and animals. It has been studied through a clinical survey that 34 per cent patients suffering from rhinitis and 12 per cent from bronchial asthma gave positive skin prickle test to parthenium pollen antigen extracts. It was studied that there was high correlation (0.66) between skin test and radio allegro sorbent. It was also observed that the pollen of parthenium also causes nasobronchial allergy in children. Parthenium reduces crops productivity and threats the nation biodiversity Earlier it was considered as a weed of wasteland but now it has invaded every crop. Initially it was considered a problem in the crops of rain fed areas only but with the increase in irrigation facility, it germinates throughout the season. Parthenium causes inhibition of nodulation in legumes. Pulses have little impact in terms of smothering effect on parthenium as the crops are slow growing and short statured in nature. Parthenium also reduces the availability of fodder crops.
Parthenium has become a menace for all of us and there is dire need to eradicate it by applying an integrated approach by amalgamating all the methods. No single method has been proved satisfactorily due to its presence throughout the year in varied climate, high reproductive rate, small and light seed weight and adaptability to survive in extreme climatic conditions. The manual removal of parthenium is effective if adapted before flowering especially in monsoon season when the soil is wet. There is need to bear the gloves or polythene sheets while uprooting it. Community efforts involving all sections of the society should be involved to manage the parthenium. Application of herbicides like glyphosate (1-1.5%) for total vegetation control specially in the waste land or metribuzin (0.3-0.5%) if grasses are to be saved in non-agricultural land are considered effective in preventing this weed spread. Alaclor (2.0kg a.i) can be used as a pre-emergence weedicide to control parthenium in soybean, rajmash, banana and tomato crop. Parthenium can be controlled by its natural enemies like insects, fungi, nematodes, snails, slugs and competitive plants. Biological control is inexpensive and poses no threat to non-target organisms, environment and biodiversity. It can also be controlled by the use of bio- agent Mexican beetle (Zygogramma bicolorata) which is natural, self-sustaining and inexpensive control measure.Detailed host-specificity tests under quarantine conditions confirmed the safety of this beetle to cultivated crops in the country. This bio- agent remains most active during rainy season and it controls the weed. This beetle completes its life cycle in 22-32 days and lives upto 5-6 generations under field conditions.The plant species like Cassia tara, Cassia seriea, Amaranthus asper, Malva pustulata etc. have capability to replace parthenium. Fast growing crops like sorghum, daincha etc. can also be grown to suppress this weed. The other way to manage parthenium by uprooting it before flowering and make compost by pit method. The compost prepared by parthenium contains more nutrients than the compost prepared by dung slurry. Farmers can make good quality compost as it does not need special equipments and infrastructure. It can also be used in papermaking, an antifeedant and phagostimulants.
Every year parthenium awareness week is organized from 16-22 August throughout the country by the National Research Centre for Weed Science, Jabalpur (M.P.) in collaboration with the Krishi Vigyan Kendras (KVKs) of State Agricultural Universities (SAUs), institutes under the Indian Council of Agricultural Research (ICAR), environmental agencies, NGOs etc. The schools, farmers, colony residents, municipalities etc. are also involved in the campaign. Various posters, technical bulletins, books etc. are distributed to the people to create awareness on parthenium management. Various awareness camps and demonstrations are organised to guide the people to eradicate this obnoxious weed by manual, biological and chemical methods. Participatory approach is needed to eradicate this allergic weed. |
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