EVALUATION OF BUTACHLOR FOR CONTROL OF SUBMERGED MACROPHYTES ALONG WITH ITS IMPACT ON BIOTIC COMPONENTS OF FRESHWATER SYSTEM

In this investigation, the efficacy of the herbicide butachlor, (N-butoxymethyl-2 chloro-2^1, 6^1 diethyl acetanilide) was tested against few common submerged macrophytes namely Hydrjlla (Hydrilla verticiltata (L.) Royale). Najas (Najas minor All.), Nechamandra (Ncchamandra alternlfolia (Roxb.) Thwaitcs) and Ottelia (Ottetia alismoides (L.) Pers.) of freshwater fish ponds. Almost complete decay of Hydrilla, Nechamandra and Ottelia was achieved at 7.5 L of active ingredient/ha/m butachlor within 15 days while the herbicide showed no negative effect on Najas, However at the same concentration of butachlor, total mortality of zooplankton and water fern Azolla (Azolla caroliniana Lamarck) OCCUlTed within seven days. In case of few freshwater fish species like Rohu (Lahro rohita}, Channa (Channa punctatus). Anabas (Anabas testitudineus) and lleteropneustcs (Heteropneustes fossilis), total mortality occurred upto 90 days after application of the same dose of butachlor but fish survived beyond 120 days of herbicide application indicating degradation of the herbicides.