Miscellaneous. 439 



The plants should be sprayed soon after they are transplanted, and 

 continued at intervals of two weeks until banked. Bordeaux should be 

 used at first and ammoniacal copper carbonate for the last applications. 



BEAN RUST. 



Uromyces appeiidiciilatus (P.) Link. 



' This rust is a disease which attacks the stems, leaves and pods of 

 the bean plant. It is characterized by the formation of roundish pustules, 

 which break and expose to the air a powdery mass of spores or "seeds." 

 These pustules bear three kinds of spores during the year. 



First, the spring spores or aecidiospores. Second, the summer 

 spores or uredospores. Third, the winter spores or teleutospores. In 

 the spring these broken pustules are filled wath a yellowish dust. This 

 dust is made up of thousands of small spring spores. This is known 

 as the cluster-cup stage of the disease. In the early summer pustules arise 

 which contain light brown spores. These are the summer spores. The 

 spring spores must germinate soon after they are formed, or they will 

 die. It was formerly thought that this was also true of the summer 

 spores ; but it has recently been found that some of them can live over 

 the winter. 



In the late summer or early autumn the contents of these spore pus- 

 tules appear to turn to a dark reddish brown or blackish color. This 

 appearance is due to the presence of another kind of spores. These 

 spores are the winter spores. They require a long period of rest before 

 they will germinate. They are capable of carrying the disease over the 

 winter season. These different kinds of spores are the fruits of the 

 rust plant. The plant itself is within the host plant. Some of these 

 small spores are carried to the epidermis of the host plant by air, water 

 or insects. Finding conditions favorable they germinate. The small 

 "roots" or hyphae grow into the host plant through some breathing pore 

 or wound. In here they branch and rebranch, spreading through the 

 whole plant. This much branched system of "roots" or hyphae is the 

 vegetative body of the rust plant, and is known as the myceHum. This 

 mycelium can be seen only by means of the miscroscope. After the 

 plant body of the rust has become quite extensive, it is ready to fruit. 

 It does this by sending up a bunch of erect hyphae from parts of the 

 mycelium, which is just beneath the epidermis of the host plant. As 

 the hyphae lengthen, they raise the epidermis into the form of pustules. 

 At the tips of these branches numerous spots will be formed, which 

 when the pustules break look like a powder. 



