Dr.Banarsi Lal, Dr.Shahid Ahamad
Parthenium hysterophorus is commonly known as congress grass or carrot weed. It is also called as Gajar Ghas, white cap or top, Gajari, Chatak Candani, Nakshtra Gida, Safed Topi etc. It is most commonly called as ‘Gajar Ghas’ as it appears like carrot plant. It is herbaceous, an annual plant belonging to subfamily Heliantheae and family Asteraceae (Compositae). It is a deadly weed infesting cropped and non-cropped areas. This weed rapidly covers the new surroundings and poses a serious threat to our environment. This weed has been fastly spreading from the last two decades.
Its origin is considered to be Mexico. In India, its occurrence was first noticed in Pune (Maharashtra) in 1955 and now it has spread throughout India. It is supposed to be introduced in India from the United States of America along with wheat and other cereals import. It has widely spread in India from Kargil region of Jammu and Kashmir to Port Blair in Andeman and Nicobar.It is said that it was introduced in Jammu and Kashmir in 1963 from Madhopur in Punjab across the Ravi River all along the national highway. After that it has been spread all over Jammu and Kashmir. Presently its infestation is alarming as it has covered large area in the state.It has been observed that this weed has reduced crop yields and has also affected biodiversity in the State. It can be seen on roadside, railway tracts, vacant lands, wastelands, agricultural, horticultural and plantation crops, industrial areas, irrigation canals etc.Presently it is considered as one of the most problematic weed. Its invasion in India has been estimated to be about 35 million hectares. It has 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 2,000m above MSL. It has also been found to occupy large area of pasture land and hence reducing the fodder availability to animals. The average height of parthenium plant is 60cm-1.5m and the average plant population is 112-828 per square meter. A single healthy plant can produce about 15,000-25,000 seeds. The seeds are very light in weight and are easily carried by wind, water or through various human activities. Its seed viability has been observed up to six years or even longer than in the soil and more than 50 per cent seeds remain viable 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.
Parthenium causes health problems in humans and animals. It has been observed that any part of the plant (even root) can cause the subsequent risk of allergic reactions. 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. Animals are equally prone to the harmful effect of the 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 on parthenium are died due to acute dysentery, itching, cryhematous, development of oedema around eyelids, dorsum of tongue, loss of hair etc. Parthenin is the chief chemical (0.3 per cent) 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 has been branded as ‘Cosmopolitan weed’, ‘National culprit’ and ‘National health hazard’ due to its serious environmental threats. 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.
There are various options for the management of parthenium but none has been found to be completely effective due to its presence throughout the year in varied climate, high reproductive rate, small and light weight and adaptability to survive in extreme climatic conditions . The manual removal is effective if adapted before flowering. Community efforts involving all sections of the society are needed to manage the parthenium. Application of herbicides like glyphosate (1-1.5 per cent) for total vegetation control or metribuzin (0.3-0.5 per cent) if grasses are to be saved in non-agricultural land are considered effective in preventing this weed spread. It can also be controlled by the use of bio agent Mexican beetle (Zygogramma bicolorata) as it is natural, self sustaining, inexpensive and is ideally suited to non-crop situations and wastelands. This bio agent remains most active during rainy season and it completely controls the weed. The plant species like Cassia tara, Cassia seriea, Amaranthus asper, Malva pustulata etc. have capability to replace parthenium. The other way to manage parthenium by uprooting it before flowering and make compost by pit method. It can also be used for vermicomposting. 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.
National Research Centre for Weed Science, Jabalpur (MP) organises many awareness programmes throughout the country by involving Krishi Vigyan Kendras, institutes under ICAR, environmental agencies, NGOs, schools etc.Various posters, folders, books and video films are distributed to the stakeholders. Sher-e-Kashmir University of Agricultural Sciences and Technology, Jammu (SKUAST-J) also organises such programmes and feedback from the stakeholders proved that people are really interested to curb this menace. SKUAST-Jammu organised the awareness week on parthenium management from 16-22nd of August. Krishi Vigyan Kendras of SKUAST-J campaigned at different places of Jammu province including schools and motivated the people to eradicate this weed. Through this programme people were guided how to eradicate this week by manual, biological and chemical practices. People from all over the province enthuastically participated in the programme and committed to curb this menace.
(The writers are: Dr. Banarsi Lal, Incharge(Head), KVK Reasi and Dr. Shahid Ahamad, Deputy Director, Directorate of Research (Sher-e-Kashmir University of Agricultural Sciences and Technology-Jammu)
