Plant- Diseases, 



59 



Sweet-Potato (Stem-Rot), continued. 



tubers, causing the tubers to rot away above, and to send up 

 sprouts below the injured portion. 

 Preventive. — Rotation. Heat the soil used for seed-bed. 

 White-Mold or Leaf-Mold (Cystopus Ipomcea-pandurancv, 

 Faii.) — The leaves become pale and brown patches appear, 

 and small whitish patches occur on the under surface. It 

 thrives upon the wild potato-vine or inan-of-the-earth 

 (Ipomcea pandurata) . 



Preventive. — Destroy the wild potato- vine upon which the 

 fungus grows. 



Remedy. — Some copper fungicide applied in a spray. 

 White-Rot. — This disease causes portions of the tuber to 

 become white and chalk-like, and sometimes the whole tuber 

 assumes a chalk-like consistency. 



Preventive. — Use only healthy stock, and probably a rota- 

 tion of crops will be useful. 

 Tomato. Blight (Cladosporium fulvum. Cooke).— Soft brown 

 irregular spots appear on the under surface of the leaves, 

 and the upper surface becomes spotted with yellow. The 

 leaves finally shrivel. Most serious in greenhouses. 



Preventive. — In houses, keep the temperature as even as 

 possible. In particular, avoid sudden changes. 



Remedy. — Bordeaux mixture or ammoniacal carbonate of 

 copper sprayed on the plants every week or ten days. 

 Rot (Macrosporium tomato). — The rotting of the nearly grown 

 or ripe fruit. 



Preventive. — The small cherry and plum tomatoes are not 

 attacked, and the old-fashioned angular sorts are compara- 

 tively free. Training the vines so as to give the fruit plenty 

 of light and air is usually useful. Heavy applications of 

 fresh stable-manure appear to augment the injury. Burn 

 all infested vines and fruits in the autumn. 



Remedy. — Spray with Bordeaux mixture. 



The bacterial potato-blight or rot also attacks tomatoes. 

 See under Potato. 

 Verbena. Rust (Oidium erysiplwides) . — A rust which appears on 

 the leaves, eventually destroying the plants. 



Preventives. — Start with perfectly healthy and vigorous 

 stock, and give good culture. In tho house, endeavor to 

 avoid drafts, but give plenty of air on bright days. 



