The accumulation and dissipation patterns of the aquatic herbicide fluridone, l-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4( 1H)-pyridinone, and its major degradation products have been determined in 40 pond and lake experiments in the United States, Panama, and Canada. The average bioconcentration factor for the total residue of fluridone plus a single major metabolite, l-methyl-3-(4-hydroxyphenyl)-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone, in several fish species was 1.33, 7.38, and 6.08 in edible tissue, inedible tissue, and whole body, respectively. Fluridone dissipated with an average half-life of 20 days in pond water and 3 months in pond hydrosoil. The treatment of small areas (0.8-4.0 ha) of large lakes resulted in more rapid dissipation due to dispersal of fluridone into the surrounding untreated water. Little or no carry-over of residues occurred prior to annual retreatments of the ponds. Mathematical models were evaluated for relating the half-life of fluridone in pond water to physical and chemical properties of the water. Fluridone, l-methyl-3-phenyl-5-[3-(trifluoromethyl)-phenyl]-4(1H)-pyridinone (I), is the active ingredient in 0 0 0 0

A method is described for the simultaneous determination of the experimental insecticide nifluridide (N-(2-amino-3-nitro-5-(trifluoromethyl)phenyl)- 2,2,3,3-tetrafluoropropanamide) and its cyclized product, EL-919 (7-nitro-2-(l,l,2,2-tetrafluoroethyl)- 5-(trifluoromethyl)benzimidazole), in water. Both compounds are extracted by passage of up to 500 mL water through two Sep-Pak C18 cartridges joined in series. The extraction is automated by using vacuum. The compounds are eluted from the cartridges with acetonitrile. Both compounds are then separated and measured by high pressure liquid chromatography with UV detection at 235 nm. Recoveries were 91.2-97.1% nifluridide and 82.7-98.0% EL-919 for deionized water samples fortified with 0.001-0.1 ppm nifluridide and 0.005-0.1 ppm EL-919. Analysis of water samples (pH 8) from bluegill and rainbow trout toxicity studies with nifluridide resulted in a half-life determination of 10 h at 13°C and 2.5 h at 20°C with nearly quantitative conversion to EL-919 within 96 h.

It has been shown that a modified, live panleucopenia virus is quite stable when stored in the medium in which it was produced.

Spores of PA 3679 were derived from vegetative cells made resistant to an initial 4.0 ppm tylosin.Rate of germination of PA 3679 spores, either from the original sensitive stock or from a resistant stock, is not affected by tylosin. Vegetative cells of PA 3679 arising from germination and subsequent outgrowth of the resistant cells are killed by 0.8-0.9 ppm of residual tylosin. This is to he compared with 0.05-0.25 ppm initial tylosin required to kill sensitive cells. The residual level of tylosin in sterile spore-recovery media is dependent on the initial tylosin concentration and the medium.