52 The Horticulturist's Rule- Book. 



Plum (Plum-leaf or Shot-hole Fungus) , continued. 



venting the fruit from maturing. The disease is some- 

 times designated simply "falling of the leaves." 



Remedies. Burn leaves as soon as they fall. Try 

 spraying in May and June with some fungicide, as soda 

 hyposulphite or Bordeaux mixture. 



PLUM POCKETS or BLADDERS [Tap&rina pruni, Tul.). 

 Causes the fruit to become inflated and hollow. These 

 "bladders" begin to appear soon after the flowers fall, 

 and continue to grow for several months, when they fall. 

 They are at first globular, but finally become oblong, 

 often reaching two inches in length. The fungus attacks 

 the fruit of the Chickasaw and American plums, and vari- 

 ous species of plum and cherry. 



Remedy. Destroy the "bladders" before they mature, 

 together with small portions of the wood on which they 

 are borne. 



POWDERY MILDEW. See under Apple. 



Plane-tree. LEAF- SCORCHING (Gl<zosporium nervisequum, 

 Sacc.). Attacks the leaves in spring, causing them appear 

 as if scorched. They finally fall off. Attacks both the 

 native and oriental planes. 



Remedy. Burn all leaves when they fall. 

 Poplar. LEAF -RUST (Melampsora populina, Lev.). An 

 orange rust attacking, during summer, the leaves of vari- 

 ous species of poplar, including the cottonwood, balm of 

 Gilead, etc, 



Remedy. Rake and burn the leaves. 



Potato. POTATO-ROT or BLIGHT (Phytophthora infestans, 

 De Bary). The spores first germinate upon the tops or 

 vines, causing the foliage to blight. The disease soon 

 spreads to the tubers, causing discolored and depressed 

 potatoes. It is a "dry rot," but other fungi attack 

 the tubers and cause the wet rot which follows. The 

 fungus may remain in the tuber during winter. 



Preventive. Plant on light or loamy, well-drained soil. 

 Plant only sound and disinfected tubers. Hill deep. 



