26 NATURAL CONTEOL OF WHITE FLIES IN FLORIDA. 



in the season by a rank growth of sooty mold (Meliola sp.), but this 

 usually occurs after the fungus has ceased spreading rapidly and on 

 pustules the majority of which would fall from the leaves before 

 spring. On the whole these two fungi are of no practical importance 

 in checking the spread of the red Aschersonia or in reducing its 

 efficacy. 



THE YELLOW FUNGUS. 



(Aschersonia flavo-dtrina P. Henn.) 



Specimens of a white-fly parasite from the grove of Mr. J. F. 

 Adams, of Winter Park, Fla., sent to Mrs. Flora W. Patterson, 

 Mycologist of the United States Department of Agriculture, in Sep- 

 tember, 1906, by Prof. P. H. Rolfs, director of the Florida Agricul- 

 tural Experiment Station, were identified by Mrs. Patterson as the 

 yellow fungus (Aschersonia Jiavo-citrina). Previously this had been 

 discovered occurring on leaves of the guava (Psidium) at Sao Paulo, 

 Brazil, in October, 1901, and described in 1902 by P. Hennigs. No 

 insect was mentioned associated with it on the guava leaves. 



Since its discovery in Florida as a parasite of Aleyrodes nuhifera 

 and A. citri it has been found in several new localities and has been 

 introduced into others. Reports and bulletins of the Florida Agri- 

 cultural Experiment Station and the Transactions of the Florida 

 Horticultural Society contain the only references to data concerning 

 the yellow fungus as a parasite of white flies. Prof. Fawcett has 

 published the most important contributions to our more technical 

 knowledge and has successfully grown artificial cultures on various 

 media. Prof. George F. Atkinson, of Cornell University, has also 

 successfully grown cultures from which infection has been secured 

 in the grove by the junior author in early October, 1907. 



DESCRIPTION. 



The yellow Aschersonia in general form closely resembles the red 

 Aschersonia, but is at once separated from it by the rich yellow 

 instead of pink or red color of its well-developed pustules. A suffi- 

 ciently clear idea of its aj^pearance may be had by referring to Plate I, 

 upper figure. (See also Plates V and VII.) During the early stages of 

 infection it is impossible to separate these two fungi by ordinary exami- 

 nation; it is only after the pycnidia, with tlioir characteristically col- 

 ored spore masses, are formed that they can be readily distinguished. 

 Prof. H. S. Fawcett states ^ that the pustules of A. aleyrodis under 

 similar conditions average less in diameter, that the pycnidial cavities 



1 Fungi parasitic upon Aleyrodes citri, Ilniversity of Slate of Florida, Special Studies, No. 1. 



