The substituted urea herbicides were rated according to their effectiveness as aquatic herbicides in this order: diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], monuron [3-(p-chlorophenyl)-1,1-dimethylurea], neburon [1-butyl-3-(3,4-dichlorophenyl)-1-methlyurea] and TCA(trichloroacetic acid) mixtures with them. They showed greatest potential in controlling certain aquatic plants in pre-emergence and early postemergence applications. However, relatively high concentrations were required to control filamentous algae ( Cladophora , Pithophora and Spirogyra ) , chara ( Chara ) , coontail ( Ceratophyllum ) , naiad ( Najas ) , and pondweeds ( Potamogeton ) for periods of time exceeding three months and up to three years. Granular formulations achieved better distribution of herbicides for control of rooted aquatic plants along the margins of lakes and ponds. Wettable powder and liquid emulsifiable concentrates were superior to granular formulations for the control of algae and emergent or floating aquatic plants. Monuron and fenuron were less toxic to fish than were diuron and neburon. The TCA mixtures were somewhat more toxic than the simple ureas. Some species of fish were more sensitive than others and fingerlings more sensitive than adults of the same species. Fish-food organisms were reduced appreciably in plastic enclosures at herbicidal concentrations.

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USGS1964

Simazine and other s-triazine compounds as aquatic herbicides in fish habitats

This investigation studied simazine (2-chloro-4,6-bis(ethylamino)- s -triazine), atrazine (2-chloro-4-ethylamino-6-isopropylamino- s -triazine), propazine (2-chloro-4,6-bis(isopropylamino)- s -triazine), and prometone (2-methoxy-4,6-bis(isopropylamino)- s -triazine). Preemergence applications of granular formulations of simazine on attaclay or calcium sulfate of simazine at 1 to 2 ppmw controlled Potamogeton , Najas , Ceratophyllum , Heteranthera and Zannichelli a. Higher rates were required to control filamentous algae ( Cladophora and Pithophora ) and chara ( Chara vulgaris ). Early postemergence applications of wettable powder to submersed aquatics and filamentous algae were often effective. Atrazine gave similar results. Concentrations of 0.5 to 1.0 were effective in controlling Cladophora and Pithophora and three species of Potamogeton in pond applications. Spray applications, generally, were more effective than broadcasting granular atrazine. Propazine and prometone did not control submersed species in concentrations up to 3 ppmw. Simazine had a relatively high margin of safety with respect to acute toxicity to fish. It was less toxic than propazine, prometone or atrazine. Granular forms were less toxic than wettable powder or emulsifiable concentrates. Laboratory tests on bottom organisms gave an acute LD 50 toxic dosage of 28 ppmw. Field observations did not demonstrate a serious reduction in the production of bottom organisms. However, the control of aquatic vegetation brought about ecological changes affecting bottom dwelling and weed clinging organisms. These changes would affect certain fishes with special food habits.

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USGS1964

Dichlobenil as a herbicide in fish habitats

Application of 20 to 40 lb/A dichlobenil made prior to emergence accomplished various degrees of control of pondweeds ( Potamogeton diversifolius , P. foliosus , P. pectinatus , P. pusillus ) and a slender naiad ( Najas flexilis ). Coontail ( Ceratophyllum demersum ) was affected only by the higher dosage. Limited control and growth inhibition was achieved on several forms of algae in early spring applications. However, applications made to rooted submersed aquatic plants and filamentous algae ( Cladophora , Pithophora and Chara ) at postemergence stage of development had little herbicidal effect. Dichlobenil was not acutely toxic to fish at herbicidal concentrations. The range of median tolerance limits was 10 to 20 ppmw for pumpkinseed ( Lepomis gibbosus ), bluegill ( L. macrochirus ), redear sunfish ( L. microlophus ), and largemouth bass ( Micropterus salmoides ).

Missouri↗

USGS1964

Toxicological effects of herbicides on the fish environment Part 1

Abstract has not been submitted

Water and Sewage Works↗

USGS1964

Toxicological effects of herbicides on the fish environment Part 2

Abstract has not been submitted

Water and Sewage Works↗

USGS1964

Laboratories and methods for screening fish-control chemicals

Abstract not submitted to date

Investigations in Fish Control↗

USGS1963

Endothal derivatives as aquatic herbicides in fishery habitats

The disodium salt of 3,6-endoxohexahydrophthalic acid (disodium endothal) and the derivative identified by the manufacturer as the di- N,N ′-dimethylococoamine salt of endothal (coded as TD-47) were particularly effective upon submersed species of aquatic vegetation as contact herbicides. Disodium endothal at concentrations of 0.5 to 10.0 ppmw was effective in controlling approximately 50 per cent of the 19 species of plants involved in 270 tests. TD-47 at concentrations of 0.02 to 10.0 ppmw trolled 77 per cent of the 11 plant species in 94 tests. Algae ( Chara, Cladophora, Pithophora , and Spirogyra ) were more effectively controlled by TD-47 than by disodium endothal. Although TD-47 was at least 10 times more herbicidal than disodium endothal, it was about 100 times more toxic to fish. Disodium endothal was more than 50 per cent effective on submersed aquatic plants at rates in excess of 2.5 ppmw with a wide margin of safety in fish (4- to 10-fold). Disodium endothal had a median tolerance limit ranging from 95 to 150 ppmw in the aggregate of nine fish species tested extensively. Median tolerance limits for TD-47 ranged from about 0.06 to 0.3 ppmw for five species of fish. TD-47 applied at a concentration lethal to fish (0.3 to 1.0 ppmw) was effective as a dual management tool in controlling vegetation and achieving partial or complete renovation of stunted fish populations. Young, growing vegetation was most susceptible to control, and best results were achieved at water temperatures exceeding 60 F. Higher rates were required to kill plants as they matured and stands became dense. Endothal liquid formulations were superior to granules in controlling algal mats, floating and emergent plants. Granules were more effective on submersed rooted plants. TD-47 residues were of short duration. The rate of disappearance depended on time and concentration. Detectable residues disappeared within 8 days following application of 0.3 ppmw and within 2 weeks for 0.6 ppmw. However, 1.0 to 3.0 ppmw took up to 25 days to disappear. Some residues were found in fish-food organisms from treated enclosures 3 weeks after application. Fish flesh showed no absorption of endothal-armeens at sublethal concentrations. Intraperitoneal injection of endothal into fish produced a disturbance of the osmoregulation. The physiological effect of endothal was measured by chemical analysis of blood serum.

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