818 Journal of Agricultural Research vol. vi, No. 21 



weber 1 and by Carpenter 2 to be identical with F. trichothecioides Wollenw. 

 Wilcox, Link, and Pool 3 found that their fungus was incapable of attack- 

 ing the tubers through the eyes or lenticels and that it was incapable of 

 attacking the growing plants. Jamieson and Wollenweber, 3 however, 

 working with F. trichothecioides obtained from western potatoes, found 

 that F. trichothecioides was capable of attacking the growing plant, and 

 they also obtained infections through the unbroken skin of the tuber by 

 rubbing the inoculum over the surface. Their results were obtained 

 under the extremely humid conditions of the Department greenhouses 

 at Washington, D. C. 



Working with the same fungus, the writer was unable under the west- 

 ern field or laboratory conditions to produce infection through the 

 unbroken skin of the potato tuber or to produce an infection in any part 

 of a growing potato plant. His results agree in the main with those ob- 

 tained by Wilcox, Link, and Pool, 4 thus further establishing the identity 

 of F. trichothecioides with the so-called F. tuberivorum. 



Preliminary work on this potato-tuber disease was begun in 191 2, when 

 the author was connected with the Agricultural Experiment Station of the 

 University of Idaho. During the fall of 191 2 and the spring of 191 3 

 potato shippers reported heavy losses in carload lots of potatoes en route 

 from Idaho and Utah to eastern and southern markets. Examination of 

 infected tubers from such cars invariably revealed the presence of F. 

 trichothecioides. In the fall of 191 3 the writer was enabled to begin a 

 study of storage conditions of potatoes. This study was continued up to 

 the spring of 191 6. It is safe to say that powdery dryrot can be found 

 in every potato storage cellar in the areas covered by the author's investi- 

 gations. However, when storage conditions were found to be good, 

 losses were being reduced to a minimum. 



During the whole course of the investigations, experiments leading to 

 a further knowledge of the relationship of the fungus to the disease, as 

 well as practical experiments leading to its control, were carried on. 

 These experiments were conducted in part in the laboratories in Washing- 

 ton, D. C, and in part in the field, laboratory, and storage cellar of the 

 Jerome Experiment Station, Jerome, Idaho. The work was further sup- 

 plemented by the planting of seed plots in various places in southern 

 Idaho. The results of these experiments, as set forth in this paper, 

 are believed to be of fundamental scientific importance, since they 

 throw more light on the relationship of the fungus to the disease and 

 demonstrate a fairly successful method of control. 



1 Wollenweber, H. W. Ramularia, Mycosphaerella, Nectria, Calonectria. Eine morphologisch patho- 

 logische Studie zur Abgrenzung von pilzgruppen mit cylindrischen und sichelformigen Konidienformen. 

 In Phytopathology, v. 3, no. 4, p. 206. 1913. 



2 Carpenter, C W. Some potato tuber-rots caused by species of Fusarium. In Jour. Agr. Research, v. s, 

 no. s, p. 183-210, pi. A-B (col.), 14-19. 1915. Literature cited, p. 208-209. 



3 Jamieson, Clara O., and Wollenweber. Op. cit. 



4 Wilcox, E. M., Eink, G. K. K., and Pool, Venus W. Op. cit. 



