FUNGOUS STAINING OF COTTON FIBERS. 1 



By Albert Mann, Plant Morphologist, Agricultural Technology and Cotton 

 Standardization and Grading Investigations. 



OCCURRENCE OF THE DEFECT. 



The manufacturers of certain grades of cotton fabrics are occa- 

 sionally annoyed by the appearance of bright-red or deep purple- 

 blue threads appearing in white cotton cloth, thereby greatly lower- 

 ing its commercial value. The number of such threads in a square 

 yard is extremely small, but the brilliant colors make these threads 

 very prominent. 



The American Cotton Yarn Co. has sent to the Office of Agricul- 

 tural Technology and Cotton Standardization and Grading Investi- 

 gations two sets of manufactured samples showing these defects, 

 with a request for information as to the cause. Inquiry makes it 

 practically certain that the fibers are not colored in the process of 

 manufacture. Careful microscopical examination of the colored 

 fibers gave no indication of bacteria or of fungous growth. The 

 colors were very resistant to alkalis of moderate strength, as well as 

 to bleaching agents. 



PROBABLE DISCOVERY OF THE CAUSE. 



Recently a boll of cotton was obtained from Diamond Spring, Va., 

 containing a quantity of lint that was brilliant carmine red. Exam- 

 ination showed that this was due to the presence of a fungus, which 

 was identified by Dr. H. W. Wollenweber, of the Office of Cotton 

 and Truck Disease and Sugar-Plant Investigations, as belonging to 

 the genus Fusarium. The fungus was very evident, completely 

 investing the cotton fibers and even penetrating their internal 

 cavities. It was in fruit, and the sickle-shaped compound spores of 

 this genus were abundant. 



A Fusarium grows upon various host plants in the United States, 

 including the cotton plant, which under alkaline conditions may have 

 either a strong carmine-red or an intense violet-purple pigmentation. 

 It is Fusarium metaclwoum App. and Wr. Unlike some blue and red 

 pigments in plants, the two colors are not convertible into each 



i Issued Jan. 18, 1913. 

 [Cir. 110] 27 



