254 Diseases of Truck Crops 



Rust 



Caused by Puccinia sorghi Schw. 



Corn rust is a disease which is of restricted dis- 

 tribution and which is never serious enough to war- 

 rant treatment. It is characterized by chocolate 

 colored pustules on the leaves and leaf sheaths. The 

 ascidium of this rust occurs on oxalis and is known as 

 Mcidium oxalidis Thum. The uredo and puccinia 

 stages both occur on the corn. 



WEEDS 



So far as is known, none of the Graminaceous 

 weeds are subject to the three diseases of the sweet 

 corn here mentioned. Nevertheless, weeds should 

 never be tolerated. 



