58 MISC. PUBLICATION 168, U. S. DEPT. OF AGRICULTURE 



Black Rot 



(See Apples, Black Rot, p. 14; pi. 5, G.) 



Black Spot 

 (See Quinces, Black Spot, p. 65; pi. 11, B, C.) 



Blue Mold Rot 



(Penicillium expansum and possibly other species of Penicillium) 



Blue mold rot of pear (pi. 13, A, B) usually has the same symp- 

 toms as the rot of the same name on apple. There is a form, 

 however, known as pinhole rot, which in its early stages appears 

 as numerous minute spots of decay scattered over the surface 

 of the fruit. Infection apparently takes place at lenticels in the 

 skin. As the disease progresses the spots increase in size and 

 finally coalesce, so that eventually the fruit becomes entirely 

 decomposed. 



Pinhole rot occurs on both washed and unwashed fruit. It is 

 most serious on the Winter Nelis variety, but other varieties 

 are sometimes attacked. Pinhole rot is most severe on fruit that 

 is ripened slowly; hence it is probably best controlled by main- 

 taining the fruit in a hard, green condition while in storage and 

 ripening it quickly upon removal. 



(See 56, 59.) 



Brown Rot 

 (See Apples, Brown Rot, p. 20; pis. 5, H, and 13, G.) 



Bruising 

 (See Silicate Injury, p. 63; pi. 14, G, H.) 



Bull's-Eye Rot 



The name "bull's-eye rot" is applied to two rots of pear just 

 as done for those of apple. (See also Apples, Bull's-Eye Rot, p. 22; 

 pi. 13, E.) 



Core Break-Down 



Core break-down seems to be more serious in districts having 

 cool growing seasons than in hotter ones, but it occurs in all pear- 

 growing sections. Most varieties of pears are subject to the dis- 

 ease. Clairgeau, Clapp Favorite, Early Harvest, Guyot, Jargon- 

 nelle, Le Conte, Madeleine, and Sudduth have been reported sus- 

 ceptible under New York conditions. Of the varieties grown in 

 the Northwest, Bartlett, Bosc, Cornice, and Clapp Favorite have 

 been found most susceptible. 



Various names have been applied to the disease by different 

 authors; among these are internal break-down, core rot, and 

 brown heart. As the names imply, the disease is characterized 

 by softening and browning of tissues in the region of the core 

 (pi. 14, A, B). The break-down may be closely confined to the 

 core or may extend to surrounding fiesh. Sometimes the softening 

 is most pronounced in a zone about halfway between the center 

 and the outside of the pear. In the early stage the affected tissues 

 are soft and watery, and in any stage they have a disagreeable, 



