Bentazone 灭草松，苯达松

灭草松

灭草松是一种具选择性的触杀型苗后除草剂，用于杂草苗期茎叶处理。主要用于水稻、大豆、花生、小麦等作物，防除阔叶杂草和莎草科杂草，对禾本科杂草无效。
其它名称：排草丹、苯达松。
英文名称：bentazone。
化学式：C10H12N2O3S。

理化性质
性状：纯品为无色晶体。
熔点：137-139℃。
相对密度：1.47。
蒸气压：0.46mPa (20℃)。
溶解度：(g/kg/20℃) 丙酮 1507，苯 33；乙酸乙酯 650；乙醚 616； 环己烷 0.2；三氯甲烷 180；乙醇 861； 水 570mg/L (PH 7, 20℃)。

动物毒性
灭草松原药低毒。
对眼睛和呼吸道有刺激作用。
中毒治疗：如误服，需用食盐水洗胃，催吐。避免服用含脂肪的物质（如牛奶、蓖麻油等）或酒等。可使用活性碳。

常用剂型
48%灭草松水剂，25%灭草松水剂。

适用作物
大豆、花生、小麦、水稻、玉米、蚕豆、菜豆、豌豆、甘蔗、洋葱、甘薯、马铃薯、茶园、亚麻、苜蓿、薄荷、黄芪、苏子、草坪等。

防除对象
一年生阔叶杂草和莎草科杂草。如：扁蓄、鸭跖草、蚤缀、苍耳、地肤、苘麻、麦家公、猪殃殃、荠菜、播娘蒿（麦蒿）、马齿苋、刺儿菜、藜、蓼、龙葵、繁缕、异型莎草、碎米莎草、球花莎草、油莎草、莎草、香附子等。对禾本科杂草无效。

使用方法
①稻田。水直播田、插秧田均可使用。插秧后20～30天，直播田播后30～40天，杂草生长3～5叶期，亩用有效成分64～96克，对水30升。施药前把田水排干使杂草全部露出水面，选高温、无风晴天喷药，将药液均匀喷洒在杂草茎叶上，喷药后1～2天再灌水入田。防除莎草科杂草和阔叶杂草效果显著，对稗草无效。
②大豆田。大豆1～3片复叶、杂草3～4叶期为施药适期。亩用有效成分48～96克，对水30～40公斤。用喷雾器喷洒作茎叶处理，可防除豆田苍耳、苋、蓼、猪毛菜、猪殃殃、巢菜等阔叶杂草及碎米莎草等杂草，对稗草无效。
③麦田。在小麦二叶一心至三叶期，杂草子叶至两轮叶，亩用有效成分48～96克，对水30～40公斤，茎叶喷雾防除麦田猪殃殃、麦家公等阔叶杂草。
④花生田。防除花生田苍耳、蓼、马齿苋、油莎草等阔叶草及莎草，于花生2～5叶期，亩用液剂133～200毫升(有效成分64～96克)，对水30升茎叶处理。

注意事项
1．因本品以触杀作用为主，喷药时必须充分湿润杂草茎叶。
2．喷药后8小时内不应降雨，否则影响药效。
3．本品对禾本科杂草无效，如与防除禾本科杂草的除草剂混用，应先试验，再推广。
4．高温、晴朗的天气有利与药效的发挥，故应尽量选择高温晴天施药。在阴天或气温低时施药，则效果欠佳。
5．在干旱、水涝或气温的大幅度的波动的不利情况下使用苯达松，容易对作物造成伤害或无除草效果。施药后部分作物叶片会出现干枯、黄化等轻微受害症状，一般7-10天后即可恢复正常生长，不影响最终产量。
6．苯达松对棉花、蔬菜等作物较为敏感，应避免接触。

bentazone
Herbicide
HRAC C3 WSSA 6; benzothiadiazinone

NOMENCLATURE
bentazone
Common name bentazone (BSI, E-ISO, (f) F-ISO, JMAF); bentazon (ANSI, Canada, WSSA); bendioxide (Republic of South Africa)
IUPAC name 3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide
Chemical Abstracts name 3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide
CAS RN [25057-89-0] EEC no. 246-585-8 Development codes BAS 351H (BASF)

bentazone-sodium
CAS RN [50723-80-3], formerly [92309-31-4]

PHYSICAL CHEMISTRY
bentazone
Composition ³96% pure. Mol. wt. 240.3 M.f. C10H12N2O3S Form Colourless crystals. M.p. 138 °C V.p. 0.17 mPa (20 °C) KOW logP = 0.77 (pH 5), -0.46 (pH 7), -0.55 (pH 9) Henry 7.167 ´ 10-5 Pa m3 mol-1 (calc.) S.g./density 1.41 (20 °C) Solubility In water 570 mg/l (pH 7, 20 ºC). In acetone 1387, methanol 1061, ethyl acetate 582, dichloromethane 206, n-heptane 0.5 ´ 10-3 (all in g/l, 20 ºC). Stability Very resistant to hydrolysis in both acidic and alkaline media. Decomposed by sunlight. pKa 3.3 (24 ºC)

bentazone-sodium
Mol. wt. 262.3 M.f. C10H11N2NaO3S Solubility In water 2.3 ´ 106 ppm (US EPA 1988).

COMMERCIALISATION
History Herbicide reported by A. Fischer (Proc. Br. Weed Control Conf., 9th, 1968, 2, 1042). Introduced by BASF AG in 1972. Patents US 3708277; DE 1542836 Manufacturers BASF; CAC; High Kite; Q.E.A.C.A.

APPLICATIONS
Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site. Mode of action Selective contact herbicide, absorbed mainly by the foliage, with very little translocation, but also absorbed by the roots, with translocation acropetally in the xylem. Uses A contact herbicide controlling Anthemis, Chamomilla and Matricaria spp., Chrysanthemum segetum, Galium aparine, Lapsana communis and Stellaria media in winter and spring cereals, at 1.0-2.2 kg/ha. Other crops include peanuts, maize, peas, Phaseolus beans, rice (Cyperus difformis, C. esculentus, C. serotinus, Monochoria vaginalis, Sagittaria pygmaea, S. sagittifolia, Alisma and Commelina spp., Scirpus maritimus and S. mucronatus) and soya beans (Abutilon theophrasti, Capsella bursa-pastoris, Cyperus esculentus, Datura stramonium, Helianthus spp., Polygonum spp., Portulaca spp., Sida spinosa, Ambrosia spp., Sinapis arvensis and Xanthium spp.). Formulation types SL.

bentazone
Selected products: 'Benta' (Sanonda)

bentazone-sodium
Selected products: 'Basagran' (BASF); mixtures: 'Doble' (+ acifluorfen-sodium) (Latin America) (BASF); 'Galaxy' (+ acifluorfen-sodium) (BASF); 'Storm' (+ acifluorfen-sodium) (BASF); 'Clincher Bas' (+ cyhalofop-butyl) (Dow AgroSciences)

OTHER PRODUCTS
bentazone
'Basamais' (BASF); 'Adagio' (Sipcam Phyteurop); 'Pilargran' (Pilarquim) mixtures: 'Basagran DP' (+ dichlorprop-dimethylammonium) (BASF); 'Extoll' (+ bromoxynil) (diolamine salts) (BASF); 'Impuls' (+ pendimethalin) (BASF); 'Archer' (+ MCPA+ MCPB) (Headland) Discontinued products mixtures: 'Clean Sweep' * (+ imazethapyr) (BASF); 'Dribble' * (+ dimefuron) (Feinchemie Schwebda); 'Topshot' * (+ cyanazine+ 2,4-DB) (Cyanamid)

bentazone-sodium
'Basagran Forte' (BASF) mixtures: 'Acumen' (+ MCPA-sodium+ MCPB-sodium) (MCPA may be as potassium or dimethylammonium salts) (BASF); 'Artett' (+ terbuthylazine) (BASF); 'Conclude B' (+ acifluorfen-sodium) (BASF); 'Conclude Ultra' (+ sethoxydim+ acifluorfen-sodium) (BASF); 'Conclude Xtra' (+ clethodim+ acifluorfen-sodium) (BASF); 'Laddok' (+ atrazine) (BASF, Sipcam); 'Pulsar' (+ MCPB-sodium) (BASF); 'Rezult' (+ sethoxydim) (BASF); 'Cambio' (+ dicamba-sodium) (De Sangosse) Discontinued products mixtures: 'Faster' * (+ fomesafen-sodium) (BASF); 'Manifest B' * (+ acifluorfen-sodium) (BASF)

ANALYSIS
Product analysis by rplc with u.v. detection (AOAC Methods, 17th Ed., 993.02; CIPAC Handbook, 1985, 1C, 1973) or by glc of a derivative. Residues determined by glc of a derivative with ECD (BBA Kurzfassungen zur Analytik von Pflanzenschutzmitteln in Wasser, 1989, 2, Auflage S. 42). In drinking water, by conversion to methyl ester with diazomethane, then glc with ECD (AOAC Methods, 17th Ed., 992.32). Details available from BASF.

MAMMALIAN TOXICOLOGY
Reviews FAO/WHO 83, 85, 86 (see part 2 of the Bibliography). Oral Acute oral LD50 for rats >1000, dogs >500, rabbits 750, cats 500 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2500 mg/kg. Moderately irritating to skin and eyes (rabbits). Inhalation LC50 (4 h) for rats >5.1 mg/l air. NOEL (1 y) for dogs 13.1 mg/kg b.w.; (2 y) for rats 10 mg/kg b.w.; (90 d) for rats 25, dogs 10 mg/kg b.w.; (78 w) for mice 12 mg/kg b.w. ADI (JMPR) 0.1 mg/kg [1998, 1999]. Water GV 300 mg/l (based on ADI). Toxicity class WHO (a.i.) III; EPA (formulation) III EC classification Xi; R36| R43| R52, R53

ECOTOXICOLOGY
bentazone
Birds Acute oral LD50 for bobwhite quail 1140 mg/kg. Dietary LC50 for bobwhite quail and mallard ducks >5000 ppm. Fish LC50 (96 h) for rainbow trout and bluegill sunfish >100 mg/l. Daphnia LC50 (48 h) 125 mg/l. Algae EC50 (72 h) for green algae (Ankistrodesmus) 47.3 mg/l. Bees Not toxic to bees; LD50 (oral) >100 mg/bee. Worms EC50 (14 d) >1000 mg/kg soil.

ENVIRONMENTAL FATE
Animals Metabolism studies in three different species showed that bentazone was only poorly metabolised, the parent compound being the predominant product. Only small amounts of hydroxylated bentazone metabolites could be detected. No conjugated products were found. Plants In plants, rapidly metabolised to derivatives of anthranilic acid, the principal metabolites being the 6- and 8-hydroxy derivatives, which are conjugated to sugars, forming glycosides. Soil/Environment In soil, short-lived hydroxy compounds are first formed, which rapidly undergo further degradation (R. Huber & S. Otto in Rev. Environ. Contam. Toxicol., 137, 111-134). In sunlight, bentazone undergoes rapid degradation, ultimately to CO2. It has low soil persistence: in freshly collected field soils, aerobic DT50 (lab., 20 ºC) was 14 d. In lab. degradation studies, with soils of proven biological activity, DT50 (average) was 17.8 d; DT50 (field, average) was c. 12 d; corresponding DT90 was 44 d. Koc 13.3-176 ml/g (average 42 ml/g), indicating mobility. However, when used according to good agricultural practice, bentazone is degraded more quickly than it can leach; in all lysimeter studies, average annual leachates contained <0.1 mg/l.