112 DISEASES OF ECONOMIC PLANTS 



at the time when the gelatinous horns are present on the 

 cedar apple. 



Blight' {Bacillus amylovorus (Burr.) De Toni). — ^This 

 disease has been thoroughly discussed in connection 

 with the pear and apple. It is only necessary here to 

 indicate that it is the most serious known disease of the 

 quince. The treatment is the same as that recommended 

 for this disease on other pomaceous fruits. 



Leaf blight, black spot (Fabrcea maculata (Lev.) Atk.). — 

 Both the fruit and fohage are affected by this blight, 

 the foliage spotting and falling prematurely so that the 

 vitality and vigor of the tree is much reduced. Upon the 

 fruit it causes black blotches, first seen as small brown spots 

 which soon increase in size and turn darker in color. While 

 this spot does not materially injure the fruit for use, it does 

 retard its full development and because of impaired beauty 

 decreases its selling price. 



The means of prevention consists in protecting parts 

 which have not yet been attacked by a thorough applica- 

 tion of Bordeaux mixture. Repeated trials have shown 

 that this treatment is thoroughly effective, increasing the 

 value of the quince crop very materially; the increase 

 being both in the size and the quality of the fruit. The first 

 application should be made soon after the blossoms fall, 

 and should be followed at intervals of two or three weeks 

 with two more treatments. 



Black rot {Sphceropsis malorum Peck). — ^This rot, often 

 amounting to a loss of 10 per cent, and being widely 

 distributed, is due to the same fungus which causes the 

 black rot of the apple, and the treatments recommended 

 for the apple will prove efficient for the quince disease. It 



