BULLETIN OF THE 



c 



No. 52 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief 

 January 24, 1914. 



THE ANTHRACNOSE OF THE MANGO IN FLORIDA. 



By S. M. McMuRRAN, 

 Assistant Pathologist, Fruit-Disease Investigations. 



INTRODUCTION. 



The growing of mangos in Florida is beginning to assume some 

 commercial importance. With the increase in size and value of the 

 crops, the mango blight or anthracnose has forced itself upon the 

 attention of the growers and a demand has arisen for remedial or 

 preventive measures. The writer was assigned to the investigation 

 of this disease and spent the seasons of 1912 and 1913 in Dade and 

 Palm Beach Counties, Fla., studying the trouble in the field and 

 laboratory. 



A careful canvass of the situation was made during the last week 

 of January and the first week of February, 1912, and all the trees and 

 groves that could be located between Key Largo, 40 miles south of 

 Miami, and Palm Beach, 70 miles north, were examined. It was 

 found that practically all of the seedhng trees had bloomed heavily 

 during the first two weeks in January, but that none had set fruit. 

 Most of the trees carried the dried peduncles of the January bloom 

 at this time, and many of them remained attached to the trees until 

 the middle of March, at which time a second crop of bloom appeared. 

 Several hundred of these peduncles were collected and many of 

 them while still on the trees showed spores of a fungus in abundance. 

 A number of those that did not show spores were placed in a moist 

 chamber and they all developed spores of the same type in from 

 24 to 48 hours. At the same time a number of leaves showing small, 

 irregular, grayish spots were collected and placed in moist chambers. 

 In from three to four days these leaves produced similar spores in the 

 diseased areas. Later in the season young shoots that showed black 

 spots were collected and placed in moist chambers. These also 

 produced the same type of spores from the diseased spots. In the 

 latter part of June, as the fruits were ripening, a number were col- 

 lected, the skins of which were blotched and disfigured, and these 

 likewise produced the same type of spores. (PI. I.) Portions of 

 17148°— 14 1 



