VEGETABLE AND FIELD CROPS 279 



Badly affected : Early Ohio, Early Rose, Holborn or 

 Abundance, Swiss, Snowflake. Slightly affected : Blight 

 Proof, Rural New Yorker No. 2. Not affected ; Delaware, 

 Rural Blush. 



Rot (Rhizopus nigricans Ehrbg.). — Orton ' has described 

 a soft rot of potato native to the peat lands of California. It 

 is characterized by dull brown discoloration of the skin and 

 light brown or buff coloring of the flesh, accompanied by 

 softening. Upon pressure a clear brown liquid without 

 disagreeable odor exudes. 



The disease spreads rapidly in warm weather, and entire 

 shipments may decay en route to market. It gives no 

 trouble after frost. To prevent infection the skin should 

 not be broken in handling, and all infected refuse should 

 be destroyed by fire. 



Tipburn. — The leaves die at the tips and margins, 

 blacken, roll up, and break off. The disease is widespread 

 in the northeastern United States, especially in dry, hot 

 summer weather. 



It is not due to parasites.^ 



Blackleg, bacillose {Bacillus phytophthorus Appel.). — 

 Much confusion has arisen concerning the identity of black- 

 leg, since in many instances the mere occurrence of a black 

 region upon the stem near the ground line has led to the use 

 of the term. It is thus probable that in the literature of 

 potato maladies several distinct diseases have been con- 

 fused with the " blackleg." 



A distinct, definite, and serious disease has, however, been 

 known for several years under this name in Europe and 



' Orton, W. A., U.S. Dept. Agr. Bur. Plant Indus. Circ. 23, January 

 23, 1909. " Jones, L. R., Vt. Agr. Exp. SU. Bui. 72, 1S99. 



