798 



A. S. Crafts 



Fig. 7. Comparative uptake of nine labeled compounds by roots of barley seedlings. 

 Autoradiograms above, mounted plants below. Dosage 0.01 fxc. per 4 ml. per plant. 

 Treatment times as indicated. Compounds from left to right: 2,4-D, amitrol, MH, 

 urea, monuron, dalapon, simazin, P"- O^, lAA. 



tions explain the virtues of a surfactant for use in sprays on plants 

 operating under water stress. 



Humectants such as glycerin (Table 3), glycols, and CaCL aid in 

 the attainment of liquid-liquid contact between the spray solution 

 and the water continuum in the cells. They may do more harm than 

 good imder saturated conditions as they bring about run-olT of the 

 s}Dray solution. 



Oils are used as filming agents where 2,4-D is used in controlling 

 woody plants. It holds the toxicant in intimate contact with the 

 cuticle or bark and serves to regulate penetration to a slow ordered 

 movement. 



Recent work by Leonard (personal communication) has shown 

 that amniDiiiiiin ihiocyanate included in an amitrol formulation 

 (.Amiirol-T) protects the treated foliage from rapid contact action 



