ANTHEACNOSE OF THE MAFGO IN FLORIDA. 3 



Beneath mango trees the disease can be found on the fallen leaves 

 and, as previously mentioned, the blighted peduncles frequently 

 remain in situ for many weeks. These produce spores when condi- 

 tions of moisture are suitable, and when a second bloom follows 

 before they have fallen the conditions for infection are ideal. Even 

 after they have fallen to the ground they may continue to be a source 

 of infection for some weeks. The mango branch illustrated in Plate II, 

 figure 1, was photographed on March 4, 1912, and shows a persistent, 

 diseased peduncle of the January bloom, with the young March bloom 

 appearing around it. 



It seems likely that the potential possibilities for infection are very 

 great at all times and that all that is needed is a favorable season as 

 regards moisture to produce the disease in abundance. 



It is probable that the spores do not retain their viabihty for a 

 great length of time. Pedicels showing spores of the fungus were 

 collected the last week in- February, 1912. They were kept in an 

 envelope in a laboratory drawer until July 10 of that year, when 

 attempts were made to germinate them in drops of water on glass 

 slides. A number of slides were prepared on several successive days, 

 but no germination was obtained. Inasmuch as the fresh spores 

 germinate readily under su^ch conditions, it is to be inferred that these 

 spores were no longer viable. Under tropical conditions, however, 

 fresh suppUes of spores are being continually produced throughout 

 the year. 



INFECTION EXPERIMENTS. 



Infection experiments were planned to determine whether the 

 flower clusters of the mango could be artificially inoculated with this 

 fungus and whether the results of such inoculation would be similar 

 to the natural infection observed. The experiments were limited in 

 size and should, perhaps, be repeated on a larger scale, but taken in 

 connection with the other facts presented, i. e., the constant associa- 

 tion of this fungus and this alone, as no other was found on diseased 

 inflorescences, and the observations of Bessey and Rolfs given later, 

 they seem to be sufficient to remove any reasonable doubt as to the 

 cause of the disease in Florida. A seedling tree in the Subtropical 

 Garden at Miami was selected for this work. Fourteen buds which 

 had just begun to swell were covered on February 26, 1912, with 

 manila paper bags, which were then tied securely around the branches. 

 On March 5 the bags were removed from four huds, which were about 

 2 inches long at that time. One was sprayed with distilled water 

 with an atomizer, and three with distilled water containing spores of 

 the anthracnose fungus. They were all immediately rebagged. The 

 work was done at 10 o'clock a. m. on a calm day, and no shoot was 

 exposed for more than three minutes. The spores for all the infec- 

 tion experiments were obtained from diseased panicles which had 



