168 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



(13) Light is essential to pycnidial development, no pycnidia 



forming in cultures kept in total darkness during their entire 



growth period. No longer than 6 hours' exposure to daylight 



whose intensity has been reduced to one-half that of bright diffuse 



light is required to bring about pycnidial production in cultures 



on favorable media. Electric light is effective in inducing pycni- 

 dial production. 



(14) For the control of this disease, the practice of such sanitary 

 measures as the removal of diseased plants, the use of disease- 

 free seed, and crop rotation are to be recommended. 



Acknowledgments. — The writer wishes to express his thanks to 

 Dr. B. M. Duggar for kindly direction and criticism in the latter 

 part of this work, and to acknowledge his appreciation of the 

 helpful advice of Dr. F. A. Wolf, of the department of botany and 

 plant pathology of the North Carolina Agricultural Experiment 

 Station, under whose direction this work was begun. Acknowl- 

 edgments are also due Dr. George T. Moore for the privileges 

 and facilities of the Missouri Botanical Garden. Mr. A. F. 

 Camp kindly made certain of the photographs. 



Bibliography 



Armstrong, G. M. ('21). Studies in the physiology of the fungi. XIV. Sulphur 

 nutrition: The use of thiosulphate as influenced by hydrogen-ion concentra- 

 tion. Ann. Mo. Bot. Gard. 8: 237-281. /. 1-21. 1921. 



Atkinson, G. F. ( ,( J2). A new anthracnose of the privet. Cornell Univ. Agr. 

 Exp. Sta., Bui. 49: 306-314. /. 1-4. 1892. 



Barre, H. W. ('12). Cotton anthracnose. S. C. Agr. Exp. Sta., Bui. 164: 1-22. 

 pi. 1-7. 1912. 



Clark, W. M., and Lubs, H. A. ('17). The colorimetric determination of hydrogen- 

 ion concentration and its applications in bacteriology. Jour. Bact. 2: 1-34, 



109-136, 191-236. /. 1-8. 1917. 

 Coons, G. II. ('16). Factors involved in the growth and pycnidium formation of 



Plenodomus fuscomaculans. Jour. Agr. Res. 5: 713-785. 1916. 

 ■ — , and Levin, E. ('20). The relation of light to pycnidium formation in 



the Sphi.cropsidales. Mich. Acad. Sci., Ann. Rept. 22: 209-213. /. 1. 1920. 

 Diedicke, H. ('11). Die Gattung Phomopsis. Ann. Myc. 9: 8-35. pi. 1-3. 1911. 

 Edgerton, C. W. ( , 09). The perfect stage of the cotton anthracnose. Mycologia 



1: 115-120. 1909. 

 Harshberger, J. W. ('17). A text-book of mycology and plant pathology. 1917. 



[See p. 608.1 

 Harter, L. L. ('13). The foot-rot of sweet potato. Jour. Agr. Res. 1: 251-273. 



pi. 27-20. f. 1. 1913. 

 ,('17). Pod blight of the lima bean caused by Diaporthe phaseolorum. 



Jour. Agr. Res. 11: 473-504. pi 42~43. /. 1-11. 1917. 



