60 FUNGI AND FUNGICIDES 



Plum Pockets 



Taphrina pruni 



Although this remarkable disease has been known 

 for many years (having, indeed, been described as early 

 as 1593), its real cause has been recognized only compar- 

 atively recently. It was formerly supposed to result 

 from the attacks of insects, or from improper fertiliza- 

 tion of the ovule ; but it is now known to be due to the 

 growth of a fungus. 



Mr. Galloway states that "the 'pockets' (Plate VI) 

 make their appearance soon after the flowers have fallen, 

 attain full size and drop from the trees toward the mid- 

 dle or last of June. At first they are more or less glob- 

 ular in shape, but as they grow older they become 

 oblong, or oval, and frequently more or less curved. 

 They vary in size, but, as a rule, are from one to two 

 inches in length, and from one-half to one inch in diam- 

 eter. When young they are nearly smooth, and can be 

 distinguished from the healthy fruit by their pale yellow 

 or reddish color. As they grow older the color changes 

 to gray, the surface appearing as though it had been 

 sprinkled with fine powder, and at the same time the 

 pockets become " wrinkled. Finally they turn black, or 

 dark brown, and rattle like bladders when brought in 

 contact with any hard substance. They remain on the 

 tree in this condition for two or three days, then fall to 

 the ground and perish. Sections through the diseased 

 fruit show that the walls are quite thick, and that in 

 place of a stone there is a large cavity filled with fun- 

 gous threads and air." 



The leaves and young branches are also sometimes 

 attacked by the fungus; both become swollen and dis- 

 torted. When a tree once begins to bear the pockets it 

 usually continues bearing them during following seasons, 

 unless vigorously pruned. The red and purple varieties 



