122 THE POTATO 



less subject to it than those from heavy soils, and the 

 disease spreads most rapidly in a damp, warm, and 

 close cellar. 



2. Due to bacteria. 1 The tubers may be wholly or 

 partially soft, and exhale a disagreeable odor. Butyric 

 acid may be liberated and the destruction of the tubers 

 is slow. Contact with other potatoes should be avoided. 



If to be used for seed, in some cases depending on 

 the cause, soaking the tubers in formalin before plant- 

 ing is beneficial. 



DRY ROT may be the evidence of the presence of one 

 or more of several troubles.' 



1. Stem rot, 3 bundle blackening, dry end rot, is be- 

 lieved to be due to a fungus (Fusarium oxysporum); 

 the leaves curl, and the foliage wilts and dies. The 

 tubers show brown or blackened bundles at the stem 

 end under an apparently sound skin. The disease 

 spreads rapidly in storage, especially if the rooms are 

 warm. Some investigators advise that diseased tubers 

 should not be fed to stock, thrown on the manure-pile, 

 or planted, and that all such potatoes should be de- 

 stroyed at harvest-time or as soon as discovered. No 

 remedy is known. 



2. Due to bacteria. The tubers may be free from 

 odor, moderately firm, but more or less soft in spots, 

 showing in places a loose skin, which 3 ields to the fin- 

 ger, and under which are white, gray, or brownish 

 blotches. Soaking unaffected tubers in formalin before 

 planting is suggested. 



1 111. Bui. 40, p. 140. a HI. Bui 40 p , 39 Tex. Bu i 42( p 92 6 



* U. S. D. A. Bureau of Plant Industry Bui. 55. (N. Y.) Geneva Bui. 101, 

 pp. 83, 84; Bui. 138, pp. 632, 634. 



