Water hyacinth is one of the most successful colonizers in the plant kingdom. Its growth can be only restricted by utilizing it in different aspects.
Known for its dazzling lilac or violet flowers surrounded by a rosette of green leaves was why water hyacinth was distributed as take away gift at a cotton exhibition held in the new Orleans state of United States in the 18th century.
Soon it made its way into the state of West Bengal of India as an ornamental plant. Today it is known as ‘Bengal terror’, ‘blue devil’ and ‘noxious species’.
The weed, native to Brazil has spread rapidly to other parts of the world. It was initially introduced because of its aesthetic values in Africa, Southern Asia, and the U.S. India is currently infested by this weed in the country, affecting directly irrigation, hydroelectric generation, and navigation besides drastic reduction in fish production, aquatic crops (lotus, chestnut) and increase in diseases caused by mosquitoes.
The water hyacinth adds color and freshness to squalid muddy village ponds. But its beauty is only surface deep. With one plant capable of duplicating itself every nine days, it is a parasite which clogs waterways and chokes village ponds.
In a conversation with GnY, Dr. R.M. Kathiresan, Professor and Head, Department of Agronomy, Annamalai University Tamil Nadu who has worked extensively on water hyacinth said, “It is a bigger threat during monsoon as the water hyacinth blocks the flow of water thus inundating adjoining areas. During summer, in a water hyacinth infested lake the surface water of the pond or lake will evaporate nine times faster than in a lake with no hyacinth. The roots serve as a host to vectors of several diseases”
There are several methods available to remove water hyacinth but each has its own shortcoming. Dr. R.M. Kathiresan explains all the existing methods with their advantages and disadvantages.
He said, “Under chemical methods, herbicides are effective to control water hyacinth but none have been registered in India for use on water bodies. These herbicides would need to undergo a regulatory process and be registered under the central insecticides board. However, herbicides are registered for use on land or on terrestrial land”
Another method he mentioned was introducing the natural enemies in India to control their growth. In that case, the researcher would have to go to Brazil, looking for the natural enemies like insects. Then the insects would be to be tested as biological control agents.
Dr R M Kathiresan and his team found out that the biological approach wasn’t suitable in South Indian conditions as most of the water bodies were not perennial. During summer, the water will dry up, the hyacinth will die and so will the insects. And as winter comes, new hyacinth will come but there won’t be any insects.
Coleus Amboinicus/Aromaticus (Karpooravalli or Omavalli in Tamil).
If left in water, the allelopathy plant that produces a chemical substance that is lethal to other plants. It will kill water hyacinth in about 5 hours. About 1 liter of water would require 15 grams of dry powder from the plant. It will reduce the biomass of water hyacinth as well. But for large water bodies, it isn’t possible to produce dry powder in large amounts. Karpooravalli needs to be cultivated on a large scale to make available the required quantity of leaf powder. U Thus the same can be sprayed. However, water hyacinth leaves have a waxy coating because of which the spray isn’t affective. But if insects and the spray are used together, the method can be successful to quite a large extent.
Besides, Eichhornia crassipes (water hyacinth) reduces the availability of indigenous medicinal plants and also leads to local extinction. The impact of invasive species is much higher in aquatic ecosystems and largely unnoticed.
Karthik P, a regular volunteer at Ulsoor lake in Bengaluru said, “We have spent days cleaning hyacinth but it keeps coming back. It has always been considered a public nuisance because they cover and choke lakes and a breeding ground for mosquitoes”
Environmentalists often claim that hyacinth is a symptom and not a problem and the real problem lies in the tremendous pollution in the river and hyacinth grows rapidly when nitrate and phosphate levels increases in river water.
Dr R M Kathiresan explained, “Manual removal is laborious and expensive. For a particular recreational lake in Ooty, crore rupees were spent by the municipal corporation. To clean Ulsoor Lake in Bengaluru once, around 7000 armymen were engaged to remove it”
When Hyacinth was turned into a profit
When water hyacinth was removed by the Harike Forest Department in Punjab as a part of their habitat improvement activity, the removed hyacinth was often left in heaps for rotting or for making compost.
But in 2011, an initiative around the Harike Wildlife Sanctuary undertaken by WWF- India on a pilot scale changed the water hyacinth scenario. WWF selected two villages in close proximity to the sanctuary to promote handicraft products created from water hyacinth.
It made the transport of raw materials cheap and feasible. The women of the villages were already well-versed with knitting, embroidery and similar crafts and therefore showed special interest in learning this new skill. The panchayats of the two villages also were very supportive of the endeavor.
The women have now formed a self-help group and have started creating handicrafts using the fiber from hyacinths for sale.
The ministry of water resources needs to step up and try to popularize water hyacinth as crop manure. When mixed in smaller quantities with normal cattle food, it can be used for their feeding. While the extract from nanofibres of water hyacinth will be excellent for paper making.