IQQ POTATO DISEASE. 



The cure can only be accomplished by destroying the cause. It 

 would appear, so universal has the disease become, that to remove 

 the cause — to extirpate the fungus — is an impossibility, and really 

 we are compelled to believe that such is practically the fact. At 

 the same time a knowledge of the habits of the fungus, may enable 

 us in most cases to avoid the rot to a good degree. 



The grape fungus, Oidium Tuckeri, and other forms of mildew 

 are subdued by sprinkling with sulphur. These fungi however, 

 grow on the surfaces of the plants they injure. Since the potato 

 fungus penetrates the interior tissues of the whole potato plant, it 

 is doubtful if any effectual means of poisoning it without doing 

 injury to the potato will ever be discovered. Mowing off the tops 

 of the potato when they show symptoms of blight,^has in many 

 cases saved the tubers. In other cases it has failed, because a 

 crop of the fungus spores has notwithstanding penetrated the 

 soil to the tubers. Doubtless the removal of the tops from the 

 field altogether, in the early stages of the blight, might be effectual 

 in cases where simple mowing would not answer. Deep-planting 

 is remedial if not in all cases a remedy. It operates by putting 

 the tuber below the reach of the spores that fall on the ground from 

 the blighted foliage. We observe that deep-lying potatoes are 

 often sound, when those above are decayed. We should hence 

 expect to find that such varieties of the potato as naturally issue 

 the root-stocks and tuber-buds deep in the soil, would be less liable 

 to rot than the shallow-rooted kinds. Deep planting cannot be 

 expected to prove an entire cure in all cases, since no reason is 

 manifest why the fungus should not travel down to the tubers 

 through the root-stalks. Again, potatoes if planted too deep do 

 not sprout readily, and consequently make a feeble growth. The 

 buds of the potato tuber, like the germ of a seed, cannot make an 

 iota of progress in development, without the constant co-operation 

 of oxygen gas. If the supply of this indispensable agent is cut off 

 they perish ; if it be furnished them in insufficient quantity, they 

 grow slowly, and the process of growth is easily checked, and 

 converted into one of decay. The German peasant has a saying, 

 that " potatoes must be planted so as to hear the wind blow." 

 Potatoes sprout best when covered but two or three inches, if the 

 covering be soil. 



Dr. Kuhn, (now Professor of Agriculture in the University of 

 Halle in Prussia, formerly director of large estates in German}^ 



