PLANT-DISEASES. 57 



fall. Before buds expand in spring spray with sulphate of 

 iron or copper. When the flowers are falling, spray again 

 with Bordeaux mixture, and thereafter with ammoniacal 

 carbonate of copper or modified eau celeste, and repeat the 

 operation at intervals of a week or two until the fruit begins 

 to color. See under PEACH. 

 LEAF-RUST. See under PLUM. 

 POWDERY-MILDEW. See under APPLE. 



Chrysanthemum. LEAF-SPOT (Septoria sp.). First appears 

 as dark brown spots which increase hi size until the leaf 

 dies. Also causes cuttings to damp off. 



Eemedy. Pick and burn all diseased leaves, and then 

 spray the plant with Bordeaux mixture or ammoniacal 

 carbonate of copper. 



Corn. ROT or BURRILL DISEASE. Due to bacteria (Bacillus 

 Cloacae}. The plants are dwarfed, and unusually slender. 

 The roots become mucilaginous and decay, as do the leaf- 

 sheaths and the ears. 



No remedies or preventives are known, except rotation. 

 Once thought to cause a disease of cattle, but this is now 

 disproved. 



SMUT (Ustilago Maydis, DC.). Attacks the ears and stalks 

 of corn, producing familiar black abnormal growths. 

 Preventive. Plant seed from clean fields. 

 Remedies. Cut out smut and burn it. It is held by 

 some that the plant is infected from diseased seed, and that 

 soaking the seed in sulphate of copper or ammoniacal car- 

 bonate of copper is a preventive ; experiments upon this 

 point have thus far been unsatisfactory, however. 

 Cottonwood. LEAF-RUST. See under POPLAR. 

 Cranberry. GALL-FUNGUS or RED-RUST (Synchytrium Vac- 

 cinii, Thomas). Minute red galls or pimples upon the 

 leaves, flowers, and stems, causing the parts to become 

 misshapen and dwarfed. 



Remedies. Burn the infested plants and also wild plants 

 about the bog, which are infested. Withholding the water 

 from the bog in winter and spring may subdue it. 



