PLANT-DISEASES. 63 



Muskmelon. POWDERY MILDEW (Plasmopara Cubensis, B. 

 C.). Attacks the leaves of the melon, cucumber, water- 

 melon, and pumpkin. It causes large, angular discolorations 

 upon the upper surface of the leaf, and violet, frost-like 

 patches beneath. Badly affected leaves become ragged. 



Remedy. Bordeaux mixture. 



Other leaf-diseases are frequent upon the muskmelon. 

 Nursery Stock. Various leaf fungi attack young trees in nur- 

 sery rows, causing the foliage to blight and sometimes to fall. 



Preventives. Good tillage and well-drained soil. Strong 

 stock. 



Remedy. Spray with Bordeaux mixture. 

 GFJdema or Dropsy is a disorder of various plants under glass, 

 as tomatoes, violets, geraniums, which have insufficient sun- 

 light, stimulating temperature and soil, and too much moist- 

 ure. It has also been observed on twigs of the apple. It 

 is usually indicated by elevated corky or spongy points or 

 masses, much resembling fungous injury. The leaves curl. 

 The only remedy is to improve the conditions under which 

 the plant grows. 



Onion. RUST (Peronospora Schleideniana, Unger). The 

 leaves turn yellow about the time the onions begin to bot- 

 tom, or a little later, and wilt and die. 



Remedies. Grow on land not infected, and destroy all 

 affected onions. Spray early with copper fungicides. 

 SMUT (Urocystis Cepulce, Frost). Attacks the first leaf or 

 leaves of seedling onions, producing dark, irregular spots, 

 and killing or weakening the plants. 



Remedy. The sulphur and lime mixture drilled into the 

 ground with the seed, about an ounce of the mixture to 

 50 feet of drill. 



Orange. ORANGE-LEAF SCAB (Cladosporium) . The leaves 

 become yellow and distorted. 



Remedies. Spray with copper fungicides, or carbolic acid 

 and glycerine mixture. 



Pansy. RUST (Peronospora Violce, De Bary). Blackish or 

 brown spots upon the leaves. 



