NATURAL EFFICACY OF FUNGOUS PARASITES. 45 



Wlion tlio (lilt a ill Tal)]!': IX are cxainiuocl witJi due considoration 

 of circunistaiicos known to the authors, it aj)poars tluit tlio fungous 

 diseases in the eight gi'oves were ineffective in 1908, but produced a 

 condition in that year resultinjjj in satisfactory freedom from the 

 insects and bhickening of the fohagc in one grove in 1909 and witii 

 prospects for such a condition in at least one grove in 1910. As the 

 investigation of fungous diseases was discontinued in 1909, there are 

 no records as to the condition of the groves the following season. 

 Since the actual cause of the temporary freedom from injurious 

 attack is often obscure, as the foregoing r(^(•()rds sliow, it is evident 

 that less ck^tailed observations, such as have formed the basis of the 

 estimates of the authors of previous publications (including the 

 senior author of the present publication), have favored tlie fungi 

 ratlier than otherwise in crediting them with complete eflicacy to 

 tlie extent of one year in three. 



During 1906, 1907, 190S, and 1909 a large number of records were 

 accumulated in regard to the ellicacy of fungous diseases during those 

 years in about 25 citrus groves located in different sections of Florida, 

 mostly in Lee, ]\[anatee, Ilillsboro, and Orange counties. In several 

 instances authentic information has also been secured in regard to 

 the efficacy of the fungi in previous years, as shown by the necessity 

 for washing the fruit to remove sooty mold. 



More than one-half of the total number of records are concerning 

 hammock groves and the list includes the majority of groves in 

 Florida where the fungous diseases have been exceptionally effective 

 during the period under observation. In two instances groves have 

 been noted or authentically reported as free from blackening for two 

 successive ^'^ears after being well freed from the insects by fungous 

 diseases. These are offset, however, by several instances of groves 

 showing no benefit whatever for three or more years after the fungous 

 diseases have become well established. In the case of one grove in 

 Manatee County, unfavorably located with respect to a general 

 nursery with citrus, China trees, privets, and other food plants, it 

 had been necessar}^ for the owner to wash tJie fruit every year for a 

 period of more than 10 years, except for less than one-half, of one 

 crop. Although the red and the brown fungi were always found 

 present in a])undance at each of the several examinations made by 

 tlie authors, the trees were always found to be more or less blackened 

 and in one instance noted as being as thorouglily blackened as any 

 grove seen in Flori<hi. 



The Iiammock gi-oves of Manatee and Lee counties have offered 

 the best opportunities for observations of the fungous diseases under 

 tlie most favorable conditions. During 1906 and 1909 tlie majority 

 of tlie Manatee hammock groves were practicall}' free from blackening 

 by sooty mold, but the crop of 1907 in these same groves was as 



