42 



Research Bulletin No. g 



play an important role in determining the difference in behavior 

 i if these two < irganisms. 



TABLE X 



Dry weight (in milligrams) formed by Fusarium oxysporum and 

 F. trichothecioides in 6 days 



Discussion. — The versatility of these organisms in using various 

 carbon sources in their metabolism is of great interest. This almost 

 omnivorous ability to use carbon compounds, including the simplest 

 fatty acid, the highly oxidized fatty acids, the long carbon chain 

 acids, the alcohols, mono- and poly-hydric, glycerin and fats, the 

 mono-, di-, and poly-saccharides, including the dextrines, starches. 

 hemicelluloses, and true celluloses, assigns to them an important 

 role in the carbon cycle, and at the same time must help render 

 them the formidable and destructive enemies of the root crops that 

 they are. 



The methods suggested by Appel (2), namely, rigid inspection 

 of potato fields, immediate destruction of all plants that show the 

 slightest symptoms, quarantining of non-certified seed stock, alone 

 give promise of keeping these troubles in check. Disinfection of 

 storage cellars and of potatoes when put into storage, together with 

 storage at proper temperature, will help combat these diseases, 

 especially the dry rot induced by F. trichothecioides. 



Conclusions 



1. Fusarium tuberivorum Wilcox and Link is the same as Fusa- 

 rium trichothecioides Woll. 



2. Both Fusarium oxysporum and / ; . trichothecioides can pro- 

 duce both tuber rot and wilt of the potato plant. 



3. The wilt is induced by destruction of the root system and 

 by clogging of the xylem elements in the stem, and is. in mild 

 cases, marked by such symptoms as discoloration of leaves, curling 

 and rolling of leaves, and production of aerial tubers. 



