44 FL'XGI AXD FUXGTCIDES 



Treatment. — Spray with the ammoDiacal solution 

 of carbonate of copper as soon as leaves begin to nnfold. 

 and repeat application t^Yo or three times at intervals of 

 tAvo weeks ; or the dilute Bordeaux mixture may be 

 used, spraying in the same manner as recommended for 

 apple scab. The effect of treatment with the Bordeaux 

 mixture, as show^n in one of Mr. Galloway's experiments, 

 is illustrated in Plate IV. Discontinue the treatment 

 before the fruit is half grown. 



The Pear Blight 



Micrococcus amylovorus 



The literature of American horticulture during the 

 present century contains frequent references to the per- 

 plexing malady called pear blight. Until recently there 

 were innumerable theories as to the cause and cure of 

 the disease ; but now, thanks to the investigations of 

 Professors Burrill and Arthur, we know that it is due to 

 the presence of a specific germ — one of the bacteria— so 

 minute as to require the aid of a powerful microscope to- 

 see it. 



Pear bli2:ht is easily distins^uished from other mala- 

 dies. Limbs affected by it become dead and blackened, 

 together Avith the leaves, flow^ers or fruit which they 

 bear. The injury may be confined to one or a few limbs, 

 or may gradually extend to the whole tree. The twigs 

 of apples and certain other pomaceous fruits are also 

 liable to the disease. 



The germs of pear blight are so minute that they 

 are carried through the air by the slightest wind. They 

 seem to be unable to penetrate healthy bark, but gain 

 access to the interior of the tree through the blossoms. 

 They light upon the sticky surface of the inside of the 

 flower cup, and are able to begin developing there, pass- 

 ing down through the stem to the twig below. The 



