EFFECTS OF POST-EMERGENCE HERBICIDES ON WATER HYACINTH (Eichhornia crassipes) - TANK CULTURE EXPERIMENT

Water hyacinth (Eichhornia crassipes (Mart.) Solms) has become a major weed of rivers and dams, and a problem weed in southern parts of India. Water hyacinth has many adverse impacts on waterways, includes reduced access to water and poor quality of available drinking and irrigation water. Hence, a study was initiated to quantify the characteristics of water hyacinth and to evaluate the effect of post-emergence herbicides management methods on Water Hyacinth in tank culture in the Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, during 2007 to 2009. Tank culture experiments were carried out to quantify the characteristics and to evaluate the effects of post emergence herbicides on the management of water hyacinth in a randomized block design with three replications. Water Hyacinth mother plants grew very fast from one week after inoculation up to six weeks, after which the growth rate decreased and it involved in seed maturation, senescence and ramet production. Ramets emerged from the third week onwards and showed fast growth up to six weeks. This continuous growth process and multiplication by ramet production at a very high rate are the main reasons why water hyacinth causes enormous problems to the environment. A tank culture experiment was conducted to evaluate the efficacy of different post emergence herbicides (i.e. paraquat, glyphosate and 2, 4-D Na salt) on both water hyacinth and on the aquatic ecosystem. The results revealed that spraying of glyphosate at 10 mL/L + ammonium sulphate 20g/L + Triton 1mL/L effectively reduced the water hyacinth density as well as Water Hyacinth dry weight considerably.