R. S. DUNHAM 205 



i) The selective action of 2,4-D makes possible the killing or severe 

 injury of certain undesirable species in the presence of crop plants. 

 Differences in reaction to 2,4-D occur among species and among varieties 

 and strains of the same species. 



2) These differences may be influenced by dosage, time of application, 

 and environment. 



3) The rapidity of growth during the vegetative phase of plant de- 

 velopment and/or the stage of fiower development at the time of 

 application are important factors influencing the results from using 

 2,4-D or methoxone. 



4) The morphological reaction of crop plants is often characteristic. 

 Some abnormalities resulting from spraying with 2,4-D are listed. It is 

 pointed out that plants frequently recover completely from such initial 

 effects. 



5) Increase in the protein content of wheat and barley and reduction 

 of the oil content and iodine number of the oil in flax have been reported. 

 Varietal differences have been found to this reaction in flax. The 

 viability of seed from crop plants sprayed with 2,4-D at stages before 

 bud has not been injured. 



REFERENCES 



1. Aberg, Ewert and Denward, Thore, Atin. Royal Agri. Coll. of Sweden, 



14:366 (1947). 



2. Albrecht, H. R., /. Am. Soc. Agron., 39:163 (1947). 



3. Arakeri, H. R. and Dunham, R. S., Uni. of Minn. Tech. Bull. 190 



(1950). 



4. BucHHOLTZ, K. P., Res. Rep. ^th Ann. N. Cent. Weed Cont. Conf, Sect. Ill, 



No. I (1948). 



5. , ibid., Sect. Ill, No. 10 (1948). 



6. , ibid., Sect. Ill, No. 60 & 61 (1948). 



7. Buckley, G. F. H., ibid., Sect. Ill, No. 62 (1948). 



8. Carder, A. C, ibid., Sect. Ill, No. 12 (1948). 



9. Corns, W. G., ibid.. Sect. Ill, No. 16 (1948). 



10. Crafts, A. S., Bull. Dept. Agri. Calif, 35:34 (1946). 



11. Derscheid, Lyle a., Proc. ^th Ann. Meet. N. Cent. Weed Cont. Conf, 



21 (1948). 



12. , Stahler, L. M., and Kratochvil, D. E., Res. Rep. ^th Ann. N. 



Cent. Weed Cont. Conf, Sect. Ill, No. 11 (1948). 



13. Dunham, R. S., Proc. ^th Ann. Meet. N. Cent. Weed Cont. Conf, 228 (1948). 



14. , Crim, R. F., and Heggeness, H. G., Uni. of Minn. Agri. Ext. 



Pamph. 168 (1948). 



15. , and Robinson, R. G., Res. Rep. ^th Ann. N. Cent. Weed Cont. 



Conf, Sect. Ill, No. 40 (1948). 



