130 THE SOILS .\ND CROPS OF THE FARM. 



of the wheat. This is the red rust of wheat and other 

 cereals. These spots are one of the fruiting stages 

 and are composed of spores (Uredspores) \^hich repro- 

 duce themselves quickly, thus spreading the disease 

 rapidly. About the time the kernels begin to harden 

 or in about two weeks from, the time the red rust ap- 

 pears, long black lines appear upon the leaves and 

 stem. This is the black rust. These lines are com- 

 posed of spores (Teleutospores) which live over winter 

 and convey the disease to the barbary bushes. Red 

 and black rust are different fruiting stages of the same 

 plant. The red rust spores can produce the rust 

 plant in the wheat directly but have not generally 

 been supposed to stand freezing weather. The black 

 rust spores live over winter but have not generally 

 been supposed to cause the disease directly. 



From this brief history it would seem that in order 

 to prevent the disease it would only be necessary to 

 eradicate the barbary bushes, upon which appear the 

 first stage of the disease. This has been done in 

 many places in England, where stringent laws on the 

 subject have been enacted. On the other hand, how- 

 ever, there are, without doubt, in this country places 

 where for a radius of fifty miles a barbary bush never 

 grew and yet wheat and other cereals rust. It seems 

 probable that there are other plants upon which the 

 first stages develop — perhaps common weeds — or that 

 it is not necessary for the plant to go through always 

 all the stages of its' development. 



There is no knov/n remedy against the disease. 

 Moist, damp weather causing succulent growth when 

 the wheat is developing the kernel, seems to be favor- 

 able to the growth of the rust. Damp weather is, 



