134 TOMATO CULTURE 



poor physical condition, also favor the development 

 of the disease after transplanting. 



Western blight (Yellows). In the North Pacific 

 and Rocky Mountain states, serious losses are an- 

 nually caused by a disease apparently unlike any east- 

 ern trouble. It is marked by a gradual yellowing of 

 the foliage and fruit. Development is checked, the 

 leaves curl upward and the plant dies without wilting. 

 The nature and cause of this disease is as yet unknown. 

 It appears to be worst on new land. Experiments 

 that have been made indicate that in older cultivated 

 fields thorough preparation of the soil, manuring and 

 cultivation, combined with care in transplanting to 

 avoid injuring the roots and checking growth, will 

 greatly restrict the spread of this blight. 



DISEASES CAUSED BY PARASITES 



There are several fungous parasites of tomatoes, 

 which, for the readers convenience, may be briefly men- 

 tioned and the treatment of all discussed together. The 

 first three are indeed somewhat difficult to tell apart 

 without a microscope, as they produce a similar effect 

 on the leaves and all yield to the same treatment 

 thorough spraying with Bordeaux mixture. 



Leaf spot (Septoria lycopersici Speg.) has been 

 widely prevalent and injurious during recent years. 

 It produces small, roundish dark-brown spots on leaves 

 and stems. The lower leaves are attacked first and 

 gradually curl up, die and fall off. The vitality of the 

 plant is reduced and it is only kept alive by the young 

 leaves formed at the top. 



