DISEASES OF LETTUCE. 34? 



will be able to destroy any spores that form on the out- 

 side of the leaves, and if the entire surface of the leaves 

 is thus protected, any spores that may come in contact 

 ■with the healthy leaves will be kept from germinating, 

 and the spread of the disease will be prevented. 



DISEASES OP LETTUCE. 



If properly handled, there is little danger from the 

 attack of any disease, but unless the soil, the temper- 

 ature and moisture, are suited to the crop, one or more 

 troubles may make their appearance, and greatly injure, 

 if they do not entirely destroy it. 



The one most to be feared is commonly known as 

 "Rot." It attacks the under leaves in some cases and in 

 others the inner leaves, causing them to rot off. If, 

 when the lettuce is nearly grown, the air is too warm 

 and close, especially if a large amount of water has been 

 used, the disease is quite likely to appear. Heavy, com- 

 pact soil that does not dry out, is also favorable to the 

 appearance of the disease. The remedies will be entirely 

 preventive and will be merely to correct the conditions 

 under which the plants are grown, by using a light, 

 sandy soil, made very rich ; keeping the temperature 

 under 45 degrees at night for the cabbage varieties, and 

 not allowing it to get to 50 for Grand Rapids and similar 

 varieties ; giving an abundance of fresh air during the 

 day ; and carefully regulating the amount of water sup- 

 plied. If the disease has appeared, after correcting, so 

 far as possible, the conditions that have brought about 

 its appearance, the spores of the disease can be destroyed, 

 ind its further spread prevented by evaporating sulphur 

 in the house, taking care that it does not take fire. 



The fungus that causes the rot is known as Botry- 

 tis vulgaris, and as it can develop in decaying vegetable 

 latter, care should be taken that the manure is well 

 rorked into the soil. 



