New York Agricultural Experiment Station. 210 



as to girdle the plant or separate portions from the main stem. 

 That a wound appears to be necessary for the fungus to enter the 

 tissue is suggested by Clinton's 4 observations. He has found the 

 "inconspicuous grayish mealy growth" of the Corticium or fruiting 

 stage on the stalks of the potatoes near the surface of the ground, 

 and no injury was done to the stem at that point. He visited several 

 fields and found that 15 to 20 per ct. of the plants showed this con- 

 dition. To this same fungus Selby 5 attributes the rosette of the 

 potato, and Rolfs 6 reports that the occurrence of aerial tubers may 

 be explained partially by its presence. However there is no doubt 

 that other factors may bring about similar effects. 



PREVIOUS LITERATURE. 



Since Loew's discovery 7 of the germicidal action of formalde- 

 hyde, in 1888, a great deal has been written on the subject of fumi- 

 gation and disinfection for bacteria and fungi. The disinfection of 

 seed potatoes was first taken up by Bolley 8 who has recommended 

 the use of corrosive sublimate (mercury bichloride) solution for 

 potato scab. Later, Arthur 9 found that a formaldehyde solution 

 gave just as good results and was safer to handle. These experi- 

 ments have been repeated and the conclusions confirmed by numerous 

 othei experimenters. The formaldehyde gas treatment for seed 

 potatoes orginated with Jones and Morse as described in Bulletin 

 No. 369, page 386. 



It is generally taken for granted that the treatment made for 

 scab is also effective in killing Rhizoctonia. Rolfs 10 conducted 

 extensive field tests of the dip method of treating Rhizoctonia, and 

 .oncluded that the mercury bichloride solution was effective in 

 controlling it; also that formaldehyde solution gave less favorable 

 results. Selby, 11 in his first report on the potato rosette (which 



4 Clinton, G. P. Report of Botanist. Conn. Sta. Rpt. for 1904:325. 



5 Selby, A. D. A Rosette Disease of Potatoes. Ohio Sta. Buls. 139 and 145. 1903. 

 6 Loc. ait. Bui. 70. 



7 Loew, O. Physiologische Notizen iiber Formaldehyd. Ber. Gesell. Morph. u. 



Phys. zu Munchen. 1888. 

 8 BolIev, H. L. Potato Scab and Possibilities of Prevention. N. Dak. Sta. Bui. 4. 



1891. 

 9 Arthur, J. C. Formaldehyde for Prevention of Potato Scab. Ind. Sta. Bui. 65. 



1897. 

 lu Loc. cit. Bui. 91. 

 ll Loc. cit. Bui. 139:58. 



