PHYSICAL CHEMISTRY Kresoxim methyl

Mol. wt. 313.4 M.f. C 18 H 19 NO 4 Form White, mildly aromatic crystals. M.p. 98-100 °C V.p. 2.3 ' 10 -3 mPa (20 oC) K OW logP = 3.4 (pH 7, 25 oC) Henry 3.6 ' 10 -4 Pa m 3 mol -1 S.g./density 1.258 kg/l (20 °C) Solubility In water 2 mg/l (20 oC). Stability Hydrolysis DT 50 34 d (pH 7), 7 h (pH 9); relatively stable at pH 5. pKa None in range 2-12

COMMERCIALISATION Kresoxim methyl

History Discovered by BASF AG in 1983. Reported by E. Ammermann et al. ( Proc. Br. Crop Prot. Conf. - Pests Dis., 1992, 1 , 403) . In production since 1995 and introduced in 1996. Patents EP 253213; US 4829085 Manufacturers BASF

APPLICATIONS Kresoxim methyl

Biochemistry Inhibits mitochondrial respiration by blocking electron transfer between cytochrome b and cytochrome c 1 , at the ubiquinol oxidising site. Selectivity is partly due to enzymic de-esterification within plants. Mode of action Fungicide with protective, curative, eradicative and long residual disease control; acts by inhibiting spore germination. Redistribution via the vapour phase contributes to activity. Uses Control of scab in apples and pears ( Venturia spp.); powdery mildew on apples ( Podosphaera leucotricha ), vines ( Uncinula necator ), cucurbits ( Sphaerotheca fuliginea ) and sugar beet ( Erysiphe betae ); mildew ( Erysiphe graminis ), scald ( Rhynchosporium secalis ), net blotch ( Pyrenophora teres ) and glume blotch ( Septoria nodorum ) on cereals; mildew on vegetables ( Leveillula taurica , Erysiphe spp., Alternaria spp.). Formulation types SC; SE; WG. '

MAMMALIAN TOXICOLOGY Kresoxim methyl

Reviews FAO/WHO 83, 85 (see part 2 of the Bibliography). Oral Acute oral LD 50 for rats >5000 mg/kg. Skin and eye Acute percutaneous LD 50 for rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Inhalation LC 50 (4 h) for rats >5.6 mg/l. NOEL (3 mo) for male rats 2000 ppm (146 mg/kg daily), female rats 500 ppm (43 mg/kg daily). ADI (JMPR) 0.4 mg/kg b.w. [1998]. Other Negative in the Ames test, and non-teratogenic.

ECOTOXICOLOGY Kresoxim methyl

Although it is toxic to aquatic species, exposure tests and ecological studies have shown that there is no danger of permanent damage to aquatic organisms when kresoxim-methyl is used as recommended. Birds LD 50 (14 d) for quail >2150 mg/kg. LC 50 (8 d) for bobwhite quail and mallard ducks >5000 ppm. Fish LC 50 (96 h) for bluegill sunfish 0.499 mg/l, rainbow trout 190 ppb. Daphnia EC 50 (48 h) 0.186 mg/l. Algae EC 50 (0-72 h) 63 m g/l. Bees LD 50 (48 h) (contact) >20 m g/bee. Worms LC 50 >937 mg/kg.

ENVIRONMENTAL FATE Kresoxim methyl

Animals Orally administered test compound was widely distributed and quickly eliminated; there was no bioaccumulation. The major routes of excretion were faeces and urine. Thirty two different metabolites were identified. Plants Residues in cereals and pome fruit at harvest are <0.05 mg/kg, in grapes and vegetables <1 mg/kg. Soil/Environment Rapidly degraded; in aerobic soil, or under aerobic or anaerobic aquatic metabolism, DT 50 <1 d. In soil, DT 90 (lab.) <3 d; the main metabolite is the corresponding acid. Very mobile in soil; K oc 219-372; K oc of the acid 17-24. However, in lysimeter studies, only low levels of kresoxim-methyl and its metabolite were found in leachates (R. Becker-Arnold & R. T. Hamm, Proc. 9th IUPAC Int. Congr. Pestic. Chem ., London, 1998, 2 , 6D-017).