THERE was a recent discovery of a recalcitrant and environmental pollutant weed in Malaysia, the parthenium.
Parthenium weed (parthenium hysterophorus), an invasive and obnoxious weed, is native to Mexico. It has invaded many countries including India, Australia, Ethiopia, Tanzania, Kenya, Papua New Guinea, Bangladesh, Pakistan, Nepal and Sri Lanka and caused disastrous ecological and economical losses.
In India, the weed has been rated as the “worst weed” of the century. To date there is no record of it in Malaysia. But recently in my preliminary survey, I found the weed to be present at roadsides in Batang Kali, Selangor.
The exact site is near Masjid Hulu Yam Baru on the edge of Jalan B57 and near the banks of Sungai Liam. The weed was found growing in open places, areas adjacent to the wall of some vegetable farms or in small bushes.
Some of the plants were shedding their seeds and others were even in vegetative stage, i.e. with no flowers.
The weed plants produce many five-angled white flowers with black and triangular seeds. The weed has severe allergenic effects on human and animal health. In India, at least 11 people died due to diseases caused by this weed. Among the probable human diseases are skin dermatitis/eczema, hay fever, itching and reddening of the skin and respiratory problems such as asthma and bronchitis. In livestock, it may cause allergic inflammation of mouth and udder, rashes on skin, ulceration of mouth and digestive tracts. In severe cases, the animals may die. When cows and goats eat the weed, the quality of milk is impaired due to unacceptable odour and the meat is tainted.
Direct contact with the skin, hands and feet and ingestion of parthenium pollens through the nose are dangerous for humans and animal health. When severely infected, it can be fatal. The weed spreads like wildfire in the dry forest. It produces a greater number of seeds per plant and can complete its life cycle within a month. This is due to their allelopathic nature (a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms.
These biochemicals are known as allelochemicals and have beneficial or detrimental effects on target organisms) as the weeds grow in colonial forms and affect the biodiversity of the infested area. These peculiar characteristics make weed control difficult.
I noticed during the survey that near the infested area were vegetable and water melon farms managed by private companies. It is suspected that during the importation of agricultural materials (seed, compost and implements) from parthenium-infested countries, the weed seeds may have been introduced in the area.
Since nobody in that area was aware about this weed being an environmental pollutant, it has, therefore, remained undisturbed for some time and consequently has got itself established. However, the population size of the weed at present is not extensive and can be controlled.
It is recommended that detailed weed survey be done in other areas to ascertain the actual status of weed infestation in the country. Proper eradication programmes should also be initiated as soon as possible. Integrated weed management involving chemical control and physical removal should be done. For protection during weed control practices in the field, hands and faces should be well protected with hand gloves and masks.
After uprooting the weeds, they should be burned in a deep pit and then buried to a depth of one metre. Community awareness should be adopted through different media channels to inform Malaysians on how they can partake in early eradication programmes to avoid this alien weed species from becoming a potential ecological disaster.
By Dr S. M. Rezaul Karim, professor, Faculty of Agro-based Industry, Universiti Malaysia Kelantan
UNIVERSITI Malaysia Kelantan has found that seedlings of a deadly plant of the genus Parthenium are growing wildly in Batang Kali, reported Berita Harian.
UMK said the seedlings of the noxious weed were at dangerous levels and “could be a national threat”.
“About 300,000 to three million seedlings were discovered at depths of zero to 20cm below the ground at five locations in Ulu Yam Baru,” said UMK researcher Dr Norhafizah Md Zain.
She added that the seedlings were found near vegetable farms, fruit plantations, animal farms and waste disposal areas.
Dr Norhafizah said Parthenium was known as “the worst weed in the world” because it affects productivity and biodiversity of plants besides causing allergies to animals and humans.
Parthenium is gazetted in the Plant Quarantine Act of 1976 as “a dangerous grass that needs to be controlled and removed”.
“The plant causes bad allergies like peeling skin, swollen eyes, rashes, itch on the mouth and nose, and continuous coughing,” said Dr Norhafizah.
Friday November 21, 2014 MYT 12:00:00 AM