Theses and Dissertations

Title: A preliminary study of the toxicity of 2,4-D to pond fishes and its effectiveness in the control of emergent species of pond weeds

Name: Snow, Jack Richard

Degree: MS

Chair: Dr. Hommer S. Swingle


University: Auburn

Location: Auburn, Alabama

Date: 1948

Pages: 98

Keywords: Toxicity,2,4-D,Emergent Pond Weeds.


The toxicity of several formulations of 2, 4-D was tested in virto on bluegill bream, Lepomis macrochirus Raf., and largemouth black bass, Micropterus salmoides lacap., as representative fishes. The salts of 2, 4-D apparently were not lethal to bass or bluegills in concentrations below 200 parts per million. The esters of 2, 4-D were extremely toxic to the fish tested at concentrations of 10 parts per million and above. The isoprophyl ester seemed to be less lethal than the two form of the butyl ester considered, causing only 14 percent mortality of the bluegills in solutions of 5 parts per million 3, 4-D. One commercial preparation of the butyl ester of 2, 4-D caused a mortality of 5 percent of the bluegills when used at a concentration of 1 part per million 2, 4-D. A similar concentration of another butyl ester preparation killed 41 percent of the bluegills tested. Indications were that the use of high concentrations of the esters in fish ponds might conceivably cause mortality of all or part of the existing fish population. The possibility appeared rather remote that sprays of the ammonium or sodium salt of 2, 4-D would be toxic to pond fishes when used for weed control. Included in the investigation was an experiment to determine the effects of certain amounts of 2, 4-D on the bass bluegill combination when applied to the ponds as it might be used in weed control treatments. Three treatments were applied to six quarter-acre ponds varying the formulation and method of application while holding the amount of 2, 4-D constant. Results from this experiment indicated that total production of fish was reduced by abiut 60 pounds per acre compared to the yield from the control ponds. Conclusive evidence of the lowered production was not obtained because of the limited number of replications. The cause of lowered production in the treated ponds was not determined, as plankton analysis of water from both treated and untreated ponds showed no signifant reduction of plankton production. In fact, one treatment showed increased amounts of plankton when compared to the untreated ponds. Several species of emergent pond weeds were satisfactorily controlled by the application of 2, 4-D sprays. High percentages of arrowhead, cattail, knotgrass, and needlerush in treated plots were killed by use of 2, 4-D in the appropriate form and concentration in a suitable carrier. Indications were that bulrush could be controlled by relatively high concentrations of 2, 4-D sprays. Parrots feather, primrose willow, and water lily were found to be susceptibleto the action of 2, 4-D, but due to the fact that much of these plants were submerged in water, roots and underwater stems survived the treatments, soon replacing the leaves and stems killed. On species of weeds resistant to the action of 2, 4-D, the salt form used were relatively ineffective in killing plants where sprays of the ester form gave good kills. However, on susceptible species any of the forms included in the experiments seemed to be effective. Usually, where the salt forms gave good resilts, a lower concentration of the esters would do equally well. A considersble amount of research is needed to adequately solve the problems involved in the use of 2, 4-D in fish ponds for control of weeds, but where susceptible species of emergent weeds occupy a fish pond the use of 2, 4-D sprays for their control seems practicable provided that excessive amounts are not applied.

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