EOTATION. 21 



have demonstrated this. One important reason for rota- 

 tion is to avoid disease. All plants are subject to some 

 disease or diseases, and a continued planting of the same 

 crop on the land causes the disease to increase, often rend- 

 ering it impossible to grow that particular crop at all. 

 This is especially true of tomatoes. Continued growing of 

 tomatoes on the same land causes the land to become in- 

 fested with blight, which it requires years to eradicate 

 from the soil. 



The prevention of disease is one of the most important 

 features of successful gardening, and the best and surest 

 way of preventing it is by judicious rotation. The old 

 adage, "an ounce of prevention is worth a pound of cure," 

 never finds a more appropriate place than here. I have 

 little faith in growing vegetables successfully where the 

 soil is infested with disease. It is sometimes advisable 

 to spray for diseases, but the safest way of obviating them 

 is to never let them get a hold on the land, and this can be 

 best accomplished by proper crop rotation. 



ROOT KNOT. 



There is a minute insect, visible only through the mi- 

 croscope, which causes enlargement of roots of many 

 crops; and where the soil is badly infested with it, it is 

 very destructive to many vegetables. Some plants are en- 

 tirely immune, others partially, while a great many suc- 

 cumb to it. It is a great pest, and once present in the 

 soil it is very difficult to eradicate. I know of no prac- 

 tical way of dealing with it, except to starve it, and by 

 planting for a number of years crops' that are immune. 



