204 . DISEASES OF ECONOMIC PLANTS 



Round Pod Wax, Refugee Wax, Burpee's White Wax, 

 Grenell's Rust-proof Golden Wax, Wardwell's Kidney Wax, 

 Dwarf German Black Wax, Early Valentine.^ 



Stem rot, pod rot (Rhizoctonia sp.). — This disease is 

 manifest in three forms:" — 



1. Damping off of seedlings. See damping off. 



2. Dry rot of the stem. In this condition the tissue is 

 dead, discolored, and dry-rotted at from 2-5 cm. above the 



upon bean seeds. After Clinton. 



ground. The rot extends to the pith and usually encircles 

 the stem, and thus so weakens the plants that they are 

 often broken by the ^vind. In any event they soon wilt 

 and die. 



3. As brown sunken areas upon pods, penetrating to 

 and discoloring the seeds. The germination of the seed is 

 not stopped by this attack, and a fruitful source of dissemi- 

 nation is thus afforded. Such seeds should be avoided.' 



Downy mildew {Phytophthora Phaseoli Thaxt.). — The 

 downy mildew is a nortiiern disease regarded by Halsted* 



' Duggar, B. M., and Stewart, F. C, N.Y. (Cornell) Agr. Exp. Sta. 

 Bui. 186, January, 1901. 



2 Fulton, H. R., La. Agr. Exp. Sta. Bui. 101, January, 1908. 



3 Hedgcock, G. G., Sci. n. .s. 19, 268, February, 1904. 

 * Halsted, B. D., N.J. Agr. Exp. Sta. Bui. 151. 



