270 Peach^Growing 



Though not serious economically, it sometimes causes some 

 loss of foliage of peach and other stone-fruits, especially 



in the South and Southwest. 



Course of development of rust. 



Peach rust occurs principally on the foliage towards 

 autumn though appearing to some extent in midsummer. 

 The fruit is rarely affected. On the lower surfaces of the 

 leaves the disease appears in the form of minute pustules, 

 light brown in color and filled with a powdery substance — 

 the spores. Later the pustules turn dark bro\\Ti or nearly 

 black. ^Miere the leaves become badly affected they drop, 

 but as stated this rarely happens to a serious extent. 



Methods of control. 



As a group of diseases, the rusts are difficult to control by 

 spraying, though it has been suggested that the spraying 

 program advised for leaf-curl would probably help materially 

 in controlling this disease when it becomes necessary to 

 take action. Because of the peculiar progress in the steps 

 in the life cycle of this rust, the presence of the wild anemone, 

 hepatica, and one or two other common wild flowers is 

 necessary to its perpetuation on stone-fruits, one stage of 

 the disease developing only on those plants. In their ab- 

 sence, the life cycle is broken and the disease cannot per- 

 petuate itself. 



California peach-blight or coryneum-hlight (Coryneum 

 beijerinkii) 



As the name suggests, this disease is of particular eco- 

 nomic importance in California. It is in that state, at least, 

 that it has attracted special attention. 



