sprays for the control of annual grasses, chickw^eed, and some other broad- 

 leaved weeds in alfalfa and clovers. CIPC is less volatile than IPC and 

 possesses greater residual weed control properties. Both are now being used 

 effectively in sonne areas for pre-emergence weed control in cotton, snap- 

 beans, lima beans, spinach, and certain other field and horticultural crops. 

 Certain of the carbamates also are used as pre-planting sprays for w^eed 

 control in canning peas and sugar beets. 



CDEC is formulated as an emulsifiable concentrate. Prolonged contact 

 with the skin will cause irritation, CDEC has shown promise for the pre- 

 emergence control of certain weeds in several vegetable crops. It is nnore 

 effective on w^eedy grasses than on broadleaved w^eeds; however, excellent 

 control of henbit and moderate control of chickweed is obtained by pre- <: 

 emergence treatments, 



EPTC has been used successfully in experiments as a pre-emergence 

 herbicide to control annual grasses and many broadleaved weeds in forage 

 legume seedlings and in certain other field and horticultural crops. It re- 

 m.ains active in the soil for short periods, EPTC is fornnulated as an emulsi- 

 fiable concentrate, is stable, and apparently noncorrosive. 



SMDC is a volatile soil sterilant that may be applied without the use of 

 an airtight cover over the soil for control of weeds, soil fungi, and nematodes. 

 This liquid may be applied in t'wo w^ays: Sprayed onto the soil with water; or, 

 mixed >vith the surface 6 -inch layer of soil, follow^ed by an application of 

 water, thoroughly wetting the surface to provide a gas seal. A 7- to 14-day 

 interval should elapse betw^een treatnnent and the planting of crops. 



The carbannates are of relatively low oral toxicity (LD^q = 3,000 to 5,000 

 mg./kg.) for rats. 



. SUBSTITUTED PHENYLUREAS 



The substituted phenylurea herbicides include 3-(p-chlorophenyl)- 1,1- 

 dimethylurea [monuron], 3-(3,4-dichlorophenyl)- 1, 1 -din-iethylurea [diuron], 

 3-phenyl-l, 1-dimethylurea [fenuron] , and 1 -n-butyl-3-(3, 4-dichlorophenyl)- 

 1-methylurea [neburon] , previously known as CMU, DCMU, PDU.andDMBU, 

 respectively. These compovuids are only slightly soluble in water. They are 

 fornnulated as wettable powders or as liquids and must be applied as suspen- 

 sions in high volumes of w^ater. They are being used for nonselective w^eed 

 control on noncultivated land. Diuron and monuron also are being used ^videly 

 as selective pre-emergence herbicides in cotton and certain other crops. 

 Fenuron is effective foi" controlling many species of brush. Neburon has the 

 least herbicidal activity and least toxicity of the substituted phenylurea 

 herbicides listed above to many crops, particularly perennial grasses. 



The substituted phenylurea herbicides are relatively low in oral toxicity 

 (L.D5o= 3,400 to 7,500 mg./kg.) for rats. 



TRICHLOROACETIC ACID [TCA] 



Several salts of trichloroacetic acid [TCA] are being used as weedkillers. 

 The sodiunn salt of TCA is used most widely. It has shown varying degrees of 



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