386 THE POPULAR SCIENCE MONTHLY. 



that it has been forced upon our attention in another and, for those 

 immediately interested, more unpleasant way. 



For the last hundred years or more, under the influence of the pe- 

 culiar methods of cultivation which have been employed by our fruit- 

 growers, various diseases have appeared from time to time in several 

 of our important fruits, and to such an extent have some of them de- 

 veloped within the last ten or fifteen years that they have completely 

 destroyed the fruit industry in some sections, and now threaten a more 

 general annihilation of one of the most enticing and profitable occupa- 

 tions for the farmer. For the last hundred years we have heard of the 

 " blight " in pear-trees, and the best records show unmistakably that 

 the disease has been on the increase during that period. So badly is 

 it developed in some fruit sections, as through Southern New York, 

 that it is a matter of extreme difficulty to find a really healthy tree. 

 For the last eighty years we have also heard of the " yellows " in 

 peaches, and here again we find that history records a constant devel- 

 opment of the affliction. So serious have its ravages proved that whole 

 sections have been deprived of the very important industry of peach- 

 culture. Not only this, but the disease is now so thoroughly estab- 

 lished, and has come to be so much a matter of inheritance, that the 

 life of the tree is greatly modified and even determined by it. The 

 peach is naturally a long-lived tree, instances brought to my notice 

 showing that it may live for upward of one hundred or more years, 

 and, if well cared for, it will certainly produce fruit for a long period. 

 At the present time, however, as in the great peach districts of Dela- 

 ware and New Jersey, we find that, owing to the certainty of disease 

 appearing, or the inherently weak constitution resulting from its pre- 

 vious operation, the period of a profitable life is limited to nine years, 

 at the end of which time the trees are rooted out of the soil as worth- 

 less. 



Twenty-five years ago the Hudson River Antwerp came into culti- 

 vation in Southern New York, and for a long time was a famous berry, 

 and made money for those who cultivated it. Within a few years a 

 disease has appeared, and to-day it is considered worthless to the fruit- 

 grower. And so it is with others of our important fruits. Diseases 

 are yearly becoming a more and more familiar foe for the horticultur- 

 ist to deal with, and a great deal of alarm is felt, and with reason, lest 

 the fruit industry in some directions be completely destroyed. Thus it 

 is that within a few years it has become imperative that something be 

 done, looking to the acquisition of facts which will enable us to suc- 

 cessfully cope with these disorders, to ward them off or arrest their 

 progress. Fortunately, the question is an important one, and so is 

 yearly claiming more careful attention from scientific men. 



Diseases arise from such a variety of causes, and are so various in 

 their effects, that we can not judge them all from the few given as 

 illustrations. Moreover, there seems to be such an inadequate concep- 



