68 horticultueist's rule-book. 



powdery spots of yellowish brown on the under surface of 

 the leaves, and reddish spots on the upper surface directly 

 above them. 



Bemedies. — Spray trees early in the season with Bordeaux 

 mixture, ammoniacal carbonate of copper, eau celeste (2), 

 or other fungicides. 



Plum-Knot or Plum- Wart {Plowrightia [^Splueria] morhosa, 

 Sacc). — A black and irregular swelling, from one to five 

 or six inches long, appearing on the small limbs of plum 

 and cherry. The point of attack is generally in the crotch 

 of young shoots or at the junction of the annual growths. 

 Peculiar to America. A very serious disease. 



Remedies. — Burn all affected parts in the fall. If the 

 knot is found upon a large limb or trunk, cut it out and 

 wash the wound with sulphate of copper. Wash the parts 

 as soon as the swelling begins to appear, with linseed oil, 

 turpentine, or kerosene, using the two latter with cau- 

 tion. A paint of red oxide of iron in linseed oil has been 

 recommended. Spraying with Bordeaux mixture in early 

 spring and during the summer will prevent attacks. There 

 should be laws in every State aimed at the destruction of 

 the knot. 



Pluj^-Pockets or Bladders (Exoascus Pnini, Fuckl.). — 

 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 reach- 

 ing two inches in length. Similar fungi attack the fruit of 

 the Chickasaw and American plums, and various species of 

 plum and cherry. 



Bemedies. — Destroy the ' ' bladders ' ' before they mature, 

 together with small portions of the wood on which they are 

 borne. Spray before buds expand with strong sulphate of 

 copper or iron, and follow with copper fungicides. 



Powdery Mildew. — See under Apple. 



Rot or Blight. — See under Peach. 

 Poplar. Leaf-Rust (3Ielampsorapopulina,li6Y.). — An orange 



