528 THE MOXTHLY BULLETIN. 



diseased tissues. The losses due to this disease will run from three to 

 ten per cent of the navel crop and as the cultivation of the navel variety 

 in the state is very extensive, the total losses are proportionately heavy. 

 "Oranges are attacked through the navel, the fungous hyphai enter- 

 ing through cracks or imperfections of the peel of those parts. The 

 cells of the pulp sacks are destroyed, and soon become black in color 

 and bitter to the taste. The peel is left uninjured until the disease has 

 made considerable progress within, but finally becomes thin and dark- 

 ened in color over the affected parts. The fungus vegetates freely 

 among the pulp sacks, which are wholly destroyed as far as the myce- 

 lium extends but destruction of tissues rarely involves more than one 

 fourth of the fruit, and is commonly confined to the tissues lying near 

 to and at one side of the navel. Infected fruit ripens prematurely, 

 showing an exceptionally high color, and soon falls from the tree. 



Fig. 324. — Drawing showing tlie course of the 

 blaclv rot from the navel to the heart of the orange. 

 (Original.) 



"The fungus inducing the disease is a new species of Alter naria, 

 and its conidia are produced upon the surface of the affected tissues. 

 The life-cycle has been studied by means of single spore cultures, and 

 detailed descriptions and illustrations are reserved for publication, to- 

 gether with facts relative to infection and preventive treatment. 



"From its habitat (inside the orange) and the character of the con- 

 idia this seems to be distinct from Alternaria tenuis Nees, on orange 

 leaves." (As far as known, the reserved descriptions have not been 

 published.) 



In an appendix to Bulletin 107, University of Florida Agricultural 

 Experiment Station, entitled "Catalogue of Rots, Spots and Blemishes 

 on Citrus Fruits in Florida, ' ' appears the following account of this dis- 

 ease by Prof. H. S. Fawcett : 



"Black Rot {Alternaria citri) — Rot beginning at the blossom (sty- 

 lar) end, especially in navel oranges, sometimes in other varieties if 

 there be a defect at the blossom end. Fruit ripening prematurely with 

 a deep color. Decay causing a blackening along the central core of the 

 fruit where the segments meet, not softening the fruit so rapidly as the 

 previous rots. Decay more confined to the interior of the fruit and 

 darker in color." 



