LUTHER BURBANK 



that were pre-eminently desirable. First and fore- 

 most it had fundamental vigor of constitution that 

 promised to supply precisely what the European 

 pear most lacked. This was manifested not only 

 in the vigor of its growth, but in its seemingly al- 

 most entire immunity to the attacks of the disease 

 that has been the scourge of the pear growers of 

 America for more than a century, and which made 

 its appearance in California about ten years ago, 

 the disease known as the pear blight. 

 THE PEAR TREE SCOURGE 



To appreciate the importance of this element 

 of resistance to disease, as manifested by the ori- 

 ental pear, it must be understood that the blight 

 is a malady of such virulent nature that when it 

 attacks the pear tree it very commonly results in 

 killing it outright. This suggests, obviously, a pe- 

 culiar susceptibility on the part of the pear. Such 

 susceptibility is manifested, unfortunately, in ex- 

 ceptional measure by the best European varieties, 

 including the Flemish Beauty and the Bartlett. 

 This, presumably, is the penalty of over-specializa- 

 tion in a certain direction, or unbalanced selection. 



Until very recently the cause of pear blight was 

 much disputed, but the agricultural experiment 

 stations have now furnished conclusive proof that 

 it is a bacterial disease, due to the presence of a 

 germ that has been named Bacillus amolovorus. 



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