EXPERIENCE OP A PRACTICAL FARMER. 11 



Two or three days give sufficient time to stop entirely all future 

 growth of the crop, unless a change in the weather occurs un- 

 favorable to the growth of this parasite. There is another kind 

 of parasite equally destructive, that causes the black blight on 

 the onion crop, similar to that which affects the potato, and re- 

 quiring the same state of the weather to produce it that is nec- 

 cessary to produce the potato rot. The parasite that causes the 

 potato rot delights in a warm, close, humid atmosphere that fre- 

 quently follows a rain. When a field of potatoes, planted either 

 early or late, is in its most vigorous growth, just before the tubers 

 begin to ripen, if such a condition of the weather then occurs, 

 this parasite will be produced. The more dense the growth of 

 vines the more liable to an attack, and it will commence in that 

 part of the field where the growth is most vigorous, and will 

 rapidly spread over the whole, unless a change in the weather 

 takes place. Some varieties of potatoes are more susceptible to 

 it than others. If the tops are cut close to the ground, when 

 first attacked, the potatoes may be saved ; otherwise, in a few 

 days, they may become more or less diseased, and decay rapidly 

 follows, in which case it is better to leave the potatoes in the 

 ground until those affected are entirely decayed. A portion of 

 the crop may thus be saved, for if dug before that time the whole 

 will be lost. 



It will be seen from what has been said, that if you plant the 

 rows wide apart, or alternate with some other crop, in order to 

 have the vines more open, they will be less liable to an attack. 



Many theories have been advanced, from time to time, as to 

 the cause and prevention of these serious hindrances to the 

 farmer's success ; but none as yet have proved satisfactory. 

 Every one, however, knows that under certain conditions mould, 

 which is a vegetable growth, will certainly appear ; that on a 

 bank of earth and stable manure, prepared in a certain way, 

 under suitable circumstances, mushrooms will surely grow. A 

 pot of earth placed in midwinter under the drip of a green- 

 house, will in a short time produce a very beautiful variety of 

 moss, and in a longer time a second variety will appear. Very 

 many instances of like character might be mentioned, all going 

 to show that certain conditions will produce certain vegetable 

 growths. 



I have endeavored to show that certain conditions of the at- 



