concentrate which must be diluted with water and applied as a spray. Most of the formu- 

 lations presently available contain 10 percent PMA by weight or approximately 1 pound 

 of active ingredient per gallon of concentrate. PMA is an effective herbicide for the 

 selective control of crabgrass in lawns. The compound is poisonous to humans and 

 other warm-blooded animals and must be handled with care. It is not presently used 

 for weed control in cultivated crops. 



POTASSIUM CYAN ATE (KOCN) „ '" 



This herbicide is a white water-soluble powder which is effective on seedling weeds. 

 It is used as a selective spray for weed control in onions, and to control crabgrass and 

 chickweed in lawns. For best results against crabgrass, it should be applied when the 

 crabgrass is small. The herbicide will often discolor lawn grasses at rates required to 

 kill crabgrass, but the discoloration will usually disappear in 7 to 10 days. 



CALCIUM CYANAMIDE ' ' '' ' 



Calcium cyanamide is a water-soluble solid. Itis usually formulated as a granulated 

 solid or pulverized powder. The by-products of calcium cyanamide decomposition in 

 acid soils possess both phytotoxic and fertilizing properties. For this reason it is often 

 used as a combination herbicide and crop fertilizer. 



This chemical has long been used as a herbicide for weed control and as a fertilizer 

 in tobacco plant beds. In recentyears ithas been used for pre-emergence weed control 

 in corn and several horticultural crops. The herbicide is also being used as a pre- 

 planting temporary soil sterilant for turf seedbeds. The chemical should be applied and 

 worked into the soil surface at least 3 weeks prior to seeding lawns and otiier turf. 

 Calcium cyanamide is also being used in turf renovation programs in some areas. 



AMMONIUM SULFAMATE 



This water-soluble white crystalline powder is most widely used for the control of 

 woody plants in areas adjacent to cotton, grapes, tomatoes, and other plants which are 

 susceptible to the phenoxy compounds. It will prevent stumps from sprouting when 

 applied to the cut surface, and will kill large trees and sprouting stumps when the 

 crystals or concentrated solutions are used in cups (ax chips) made around the base of 

 a tree or stump. 



HERBICIDAL OILS 



Herbicidal oils are usually obtained in the distillation of petroleum and coal tar. 

 Aromatic constituents usually have the greatest influence on their herbicidal properties. 

 However, recent research has shown that a number of constituents of oils affect both 

 total herbicidal activity and selectivity. Several herbicidal oils are known under a 

 variety of names such as aromatic solvent, solvent naphtha, and petroleum naphtha. 

 These oils vary widely in their herbicidal toxicity and selectivity depending on their 

 origin and composition. One specific example is a petroleum naphtha with A. P. I. 

 gravity 49 to 50, boiling range 300° to 400°F., unsaturated compounds 0.5 to 1.0 per- 

 cent, aromatic content 22 to 24 percent, sulfur compounds 0.25 to 0.30 percent, and a 

 maximum aniline point to 128°F. which is being used extensively as a directed post- 

 emergence spray for the control of seedling annual grasses and broadleaved weeds in 

 cotton. 



Stoddard solvent and light aromatic oils have been used extensively as selective 

 herbicidal oils for weed control in crops of the carrot family. Nonselective herbicidal 

 oils with high aromatic contents are being used effectively to control Johnson grass on 

 ditchbanks in the Southwest. Aromatic solvents are also being used to control aquatic 

 weeds in irrigation canals and ditches in the Western States. Diesel oil, fuel oil, stove 



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