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The spring phase occurs on the leaves of the barberry bush, a 
shrub which is cultivated for hedges. The summer and winter 
phases occur on the leaves and stems of wheat or other grain. 
If we examine the leaves of the barberry bush in the spring 
f the year we will find that they are covered with minute 
pockets, each of which is filled with a mass of golden-yellow 
spores. These spores are blown about by the wind, and if they 
fall on the leaves or stems of the wheat-plant and weather condi- 
tions are suitable they germinate and in a short time we have 
produced there a mass of rust-red spores which represent the 
summer phase of this fungus. These spores are again blown 
about and germinate immediately producing other infection. Late 
in the summer we find, in place of the red spores, a mass of black 
spores, which depresents the autumnal phase of the rust and is 
commonly known as the black rust. The black rust represents 
only a more advanced stage of the red rust. The black spores are 
especially adapted to tide over the unfavorable conditions of the 
winter season. They live over winter on the old straw or in the 
ground. In the spring of the year each germinates and produces 
a number of minute spore-like bodies which are ready to return 
to the barberry bush and begin the life cycle of this fungus anew. 
Since the barberry bush plays an important part in the life 
history of this disease one precaution which can be taken is to 
destroy these bushes which may occur in fence rows in close 
proximity to wheat fields. One of the most hopeful means of 
eventually controlling this disease is in the cultivation of rust- 
resistant varieties of wheat by a process of seed selection and it 
remains to be seen what the outcome of this line of attack will be. 
Many different plants are attacked by rusts of various kinds. 
The cedar-apple rust is one of considerable importance. While 
very different in general appearance the cedar-apple rust is closely 
related to the wheat-rust. This disease is represented by two 
stages which occur on the cedar-tree and on the leaves of the 
crab-apple respectively. The cedar-apple stage is characterized by 
gall-like swellings often an inch in diameter and the trees are often 
heavily loaded with these apple-like growths (fig. 36). People 
have been known to plant cedar-apples with the hope of producing 
