which is highly soluble in water, is the most widely used formulation. Re- 

 search indicates that it is most effective as a pre-emergence or post- 

 emergence spray for controlling perennial grasses when applied in com- 

 bination with tillage and cultural practices. Dalapon apparently possesses 

 less residual toxicity than TCA; but further research is needed to deter- 

 mine the rate of disappearance of the herbicide from the soil. Dalapon 2 

 has shown promise in experiments for weed control in sugarcane, sugar 

 beets, birdsfoot trefoil, alfalfa, and for spot treatment control of Johnson- 

 grass and other grasses in cotton. It has given effective control of cattails 

 and phragmites on irrigation and drainage canals. 



Dalapon is low in oral toxicity (LD^q = 6,590 to 8,120 mg./kg.) for rats. 



3-AMINO-l,2,4-TRIAZOLE (Amitrol) 



This herbicide is generally available as a water soluble white, crystalline 

 powder. It has shown promise for control of Canada thistle, leafy spurge, 

 Russian knapweed, quackgrass, Bermudagrass, sedges, horsetail rush, 

 cattails, and tules, and several woody plants such as poison ivy, poison oak, 

 white ash, and prickly ash. Amitrol 3 is translocated throughout the plant 

 and affects the growing points, producing chlorosis and inhibition. It is 

 quickly inactivated in most soils and appears promising for control of 

 certain perennial weeds in citrus orchards, grapes, and cranberries 

 without injuring the crops. 



Amitrol is low in oral toxicity (LD50 = 15,000 mg./kg.) for mice. 



N-1-NAPHTHYL PHTHALAMIC ACID (NPA) 



This chemical is formulated for experimental herbicidal use as the 

 sodium salt, imide, and acid. The sodium salt of NPA is available as a 

 wettable powder and as a liquid concentrate. Presently, NPA is being used 

 for pre-emergence control of grasses and broadleaved weeds in cucumbers, 

 squash, cantaloupes, and other crops in the cucurbit group. It also has 

 shown some promise for weed control in irrigated cotton in the West. 



NPA has low oral toxicity (LD 50 = 8,200 mg./kg.). 



3,6-ENDOXOHEXAHYDROPHTHALIC ACID (Endothal) 



In research studies the disodium salt of this acid has shown promise 

 for control of certain weeds in turf, alfalfa, sugar beets, and in certain 

 other crops. It is being used as apre-harvest aid, a general contact herbi- 

 cide, and chemical defoliant. 



Endothal has high oral toxicity (LDcq = 35 to 120 mg./kg.) for rats. 



2 Dalapon cannot be recommended (as of April 1, 1958) for use on birdsfoot trefoil and alfalfa since evidence 

 has not been developed to prove itwill leave no residue or/and tolerances have not been set under Public Law 518. 



3 Amitrol cannot be recommended (as of April 1, 1958) for use in citrus orchards and on grapes since evidence 

 has not been developed to prove it will leave no residue or/and tolerances have not been set under Public Law 518. 



