PLANT-DISEASES. 75 



attacks the disease can be kept in check by picking off and 

 burning the injured leaves. 



Remedies. Bordeaux mixture or ammoniacal carbonate 

 of copper sprayed on the plants every week or ten days. 



FIELD-BLIGHT or SOUTHERN BLIGHT. Attacks plants in the 

 field, causing the leaves to become dull or slightly yellowish 

 and curled, as if suffering from drought. The ends of the 

 leaves, or the individual leaflets, often die and droop. 

 Apparently common North and South. Probably bacterial. 

 It is thought to attack the potato also ; if it does, potatoes 

 and tomatoes should not follow each other upon the same 

 land. No remedy is known. 



ROOT-KNOT. A nematode disease in forcing-houses (see 

 under R, Chap. II.), causing the plants to curl their leaves 

 and become weak. Remove the crop and freeze the soil. 



ROT (Macrosporium Tomato, Cooke). The rotting of the 

 nearly grown or ripe fruit. 



Preventives. The small cherry and plum tomatoes are 

 not attacked, and the old-fashioned angular sorts are com- 

 paratively free. Training the vines so as to give the fruit 

 plenty of light and air is useful. Heavy applications of 

 fresh stable manure appear to augment the injury. Burn 

 all infested vines and fruits in the autumn. The trouble 

 is usually worst rather early in the picking season during 

 hot and moist weather. In the cooler weather of fall it 

 is rarely serious. Therefore, aim to prolong the bearing 

 season by early planting and good tillage. 



Remedy. Spraying with Bordeaux mixture seems to be 

 useful. 



The bacterial potato-blight or rot also attacks tomatoes. 

 See under POTATO. 



WINTER-BLIGHT. Probably a bacterial disease. Attacks 

 tomato plants grown under glass, causing the leaves to 

 curl and to become marked with translucent dots or spots. 

 No remedy is known. Destroy diseased plants, and do not 

 use the same soil again. 

 Verbena. RUST (Erysiphe Cichoracearum, DC.). A whitish 



