[AS.] Blight, mildew, and rust are names given to diseases which attack the stems and leaves of cereals and other plants. They first appear as small discolored patches, and gradually spread over the entire plant. This discolorat ion is due to the presence of germs or seeds of the rust fungus in the first stage of life. These germs or seeds, after several stages have been passed, settle upon the plants and live on their juices, thus doing much injury.-Rust is also the reddish-brown coating formed by oxidation on the surface of iron when exposed to a moist atmosphere.