TOMATO VIOLET 283 



roots. Where tobacco is grown under shade (as is now a common 

 practice) the soil should be steam-sterilized. 

 Tomato. BACTERIAL BLIGHT. See TOBACCO WILT. 

 BLIGHT OR SCAB (Cladosporium fulvum). Soft brown irregular 

 spots on the under surface of the leaves. The upper surface be- 

 comes spotted with yellow. The leaves finally wither and die. 

 Most serious in the greenhouse. 



Control. In mild cases the disease can be prevented by pick- 

 ing off the affected leaves. In severe cases spray with bordeaux 

 mixture, 4-4-50, at intervals of ten days. 

 DOWNY MILDEW (Phytophthora infestans). The same fungus that 



causes POTATO-BLIGHT, which see (p. 279). 



END-ROT. Not well understood, and no method of control is known. 

 LEAF-SPOT (Septoria lycopersica) . A serious disease attacking leaves 

 and stems. At first small spots appear, which spread until the whole 

 leaf is consumed. In severe cases the fruit may also be attacked. 

 Control. Spray with bordeaux mixture, 4-4-50, making the 

 first application two weeks after the plants are set out, and repeating 

 every two weeks throughout the growing season. 

 (EDEMA. A diseased condition of forced tomatoes characterized 

 by rolled or curled leaves, distended veins, and by swollen 

 areas having a frosty appearance on leaf veins, petioles and stem. 

 This condition may be brought about by insufficient light, too 

 much water in soil, excessive fertilization, high soil temperature. 

 Prevention. Avoid conditions favorable for the disease. Pro- 

 vide good ventilation in forcing-house ; in field, cultivate deep 

 and avoid topping plants. (See p. 260.) 



Violet. LEAF-SPOTS and LEAF-BLIGHTS. A number of different or- 

 ganisms are responsible. Usually not verj r destructive. 



Control. Destroy affected plants; use fresh soil for new 

 plantings; spray the foliage in the summer and fall with bor- 

 deaux mixture, 4-4-50. 



ROOT-ROT (Thielavia basicola). The same as the root-rot of 

 tobacco. The plants make poor growth, owing to the fungus on 

 the roots. 



Control Start in steam-sterilized soil, and transfer to sterilized 

 beds. 

 Wheat-Smut. See under SMUT OF CEREALS (p. 260). 



