number of large-seeded crops, including peanuts, soybeans, lima beans, 

 snapbeans, and cotton. The substituted phenols consist mainly of two 

 types. 



1. Dinitro Compounds 



These include the parent compounds 4,6-dinitro ortho secondary butyl- 

 phenol (DNBP), 4,6-dinitro ortho secondary amylphenol (DNAP), and 3,5- 

 dinitro ortho cresol (DNC)„ They are not soluble in water but are soluble 

 in oil and may be applied in an oil carrier, or emulsified with water and 

 applied as an emulsion. The parent compounds are used for pre-emergence 

 and nonselective post-emergence weed control. The salts of these com- 

 pounds, including sodium, ammonium, various amines, and others, are 

 water soluble, and are used for selective pre-emergence and post-emer- 

 gence weed control in some crops. 



The dinitro compounds are yellow dyes that impart a yellow coloration 

 to clothes and skin. These compounds can be used for weed control without 

 danger if precautions are taken to avoid inhaling the vapors or coming in 

 contact with the spray drift or spray solution. When these materials are 

 used as pre-emergence sprays, severe injury to the crop often results if 

 extremely high temperatures occur in the 2-week period following treat- 

 ment. 



The dinitro compounds are highly toxic (LD^q = 26 to 45 mg./kg.) for 

 rats. 



2. Chloro Substituted Phenols 



These include pentachlorophenol (PCP), which is soluble in oil but not 

 in water, and its sodium salt (sodium pentachlorophenate), which is soluble 

 in water. PCP is used as a fortifying agent in oil sprays for nonselective 

 weed control. PCP in oil and sodium PCP in water are also used for 

 selective pre-emergence weed control in several crops. 



The pentachlorophenols are of relatively intermediate to high oral 

 toxicity (LD^g = 50 to 500 mg./kg. for the various formulations) when fed 

 to rats. 



CARBAMATES 



The carbamates at present include isopropyl N-phenylcarbamate (IPC), 

 isopropyl N-(3 -chlorophenyl)carbamate (CIPC), and 2-chloroallyl diethyl- 

 dithiocarbamate (CDEC). They are relatively insoluble in water but are 

 formulated with organic solvents as emulsifiable concentrates. The car- 

 bamates form emulsions with water and may be applied as either low- or 

 high-gallonage sprays. They are effective as selective dormant post- 

 emergence sprays for the control of annual grasses, chickweed, and some 

 other broadleaved 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 some areas for pre-emergence weed control 

 in cotton, snapbeans, lima beans, spinach, and certain other field and horti- 

 cultural crops. The carbamates also are used as pre-planting sprays for 

 weed 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- 



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