TOMATO BLACK SPOT 269 



continue to be produced on shrivelled fruit, stems and 

 leaves. Besides, the spores persist through the winter 

 on fragments of stems, leaves and fruit, hence to 

 prevent a repetition of the disease the tops or whole 

 plant should be carefully collected and burnt. Seed 

 should not be saved from diseased fruit or even from 

 apparently healthy plants in the immediate neighbour- 

 hood of any disease. As there is danger of mycelium 

 becoming latent in the seed all the seeds with a dark 

 spot or stain in them should be rejected, only retaining 

 those that are sound and clear. 



In the matter of cultivation avoid forcing treat- 

 ment such as the use of fresh or green stable or farm- 

 yard manure, which has a tendency to induce gross 

 growth and cause the stems, leaf-stalks and fruit to 

 crack. Do not maintain a close and moist atmos- 

 phere, and admit air early to dissipate moisture which 

 is deposited on the cooler surfaces of the plant, as 

 this favours the germination of the fungus spores. 

 Keeping the atmosphere arid and restricting the 

 supplies of water for a time, and then returning to 

 genial atmospheric conditions will with generous feed- 

 ing at the roots result in cracking and render the 

 plants very susceptible to attack. Indeed, immunity 

 rests mainly upon a free atmosphere without extremes 

 of heat and cold, moisture and dryness. Prevent 

 moisture condensing on fruit and do not allow water 

 to rest upon it for any length of time. 



Thorough spraying with potassium sulphide, one 

 ounce to two and a half gallons of water, at frequent 



