K. C. BARRONS 189 



readily killed by this combination of chemicals, but they do provide a 

 practical measure of control. Perhaps further work will uncover com- 

 pounds specific for those plants that are somewhat resistant to 2,4-D 

 and 2,4,5-T. 



Although some use has been made of low-volume, high-concentrate 

 sprays of the esters of the chlorophenoxyacetic acids in oil, most of the 

 right-of-way work is conducted with more dilute sprays applied by power 

 rigs mounted on trucks. On the average better results have been obtained 

 with larger volumes applied under sufficient pressure to wet stems and 

 foliage on the inside of dense growth. Furthermore, a little drift from 

 a high concentrate spray can cause considerable damage to desirable 

 plants adjacent to rights-of-way areas. A little drift from a more dilute 

 spray carries less toxicant and is less likely to cause difficulty. Low- 

 volume spraying of right-of-way vegetation does have a place where 

 limited access by truck and limited water supply makes the use of 

 high volumes applied by power rig impractical. 



Spray operators have learned that they must pay attention to wind 

 velocity and frequently skip certain stretches of the right-of-way ad- 

 jacent to sensitive crops. Most of the instances of damage to desirable 

 plants adjacent to rights-of-way can be traced to carelessness. 2,4-D 

 and 2,4,5-T are not materials to be sprayed indiscriminately and everyone 

 using them must recognize the hazards before he begins. Areas adjacent 

 to especially sensitive crops must often be omitted from the spraying 

 program for that season even though the wind is blowing in the opposite 

 direction at the time of application. There is always the possibihty of 

 dust on the leaves of the foliage at the time of application blowing onto 

 the sensitive crop. The fact that some esters of 2,4-D are volatile has 

 frequently been pointed out as a possible cause of the reaction of crops 

 adjacent to sprayed areas. An analysis of the problem of damage to 

 plants off the right-of-way indicates that spray drift is the chief cause 

 of trouble and the blowing of dust a likely cause in some cases. Although 

 volatility may be a factor the writer feels that it has been overempha- 

 sized in relation to the other factors. 



Although the chief aim of utihties to date has been to control, and 

 insofar as possible to erradicate, woody plants on the right-of-way much 

 nongrass herbaceous vegetation has been killed by the spraying program. 

 From the ecological standpoint it is interesting to note that many 

 rights-of-way which were formerly infested with brushy growth now 



