Aquatic weeds problems in India — Challenge for management

Abstract

In India, floating aquatic weeds like water hyacinth, water fern, alligator weed and water lettuce; emergent weeds like lotus, cattail and water lily; submerged weeds like Hydrilla, bladderwort and eurasion water milfoil have become most problematic weeds and causing many detrimental effects to men and environment. Several irrigation, steel plant and hydroelectric projects in the country are suffering with massive growth of aquatic weeds besides impeding flow of water and deteriorating water quality. Weed like water hyacinth enhances rates of evaporation many folds through evapotranspiration than that of open surface, hence is responsible for great loss of water. Aquatic weeds can be controlled by using several methods like prevention, manual, mechanical, ecological, biological, chemical and through utilization. Each method has its merits and demerits. In spite of costly methods, manual and mechanical approaches are being employed frequently in India due to quick relief. In big aquatic bodies, weeds harvesters are employed. Chemical control is also being done at small scale, but its use is limited owing to lack of many registered herbicides. Use of bioagents was demonstrated successfully for control of water hyacinth and water fern by using exotic weevil Neochetina spp. and Cyrtobagaus salvinae in different parts India but for several other aquatic weeds, suitable bioagents are not available. Use of grass carp fish is increasing in India for control of submerged weeds like Hydrilla with varying degree of success.