48 NATURAL CONTEOL, OF WHITE FLIES IN FLOBIDA. 



lishing the red Aschersonia and the brown fungus in groves where 

 these white-fly enemies did not occur. 



Prof. H. A. Gossard ^ tested pinning fungus-infected leaves onto 

 leaves infested by the white fly, as also spraying with spores of the 

 fungus and fragments of its mycelium suspended in water. These 

 and certain other methods of less practical interest Prof. Gossard 

 states "have been tried by various experimenters, myself included, 

 without marked success." He adds : "However, an infection is some- 

 times started by these methods." With the knowledge concerning 

 the fungous parasites obtained up to the time of writing (1903) Prof. 

 Gossard recommended the transplanting of young trees as the most 

 reliable method of spreading the parasites. 



At the beginning of the present investigations in July, 1906, spread- 

 ing the white-fly fungi by pinning the infected leaves onto uninfected 

 trees was the method commonly employed. This method was suc- 

 cessfully used, together with the so-called tree-planting method, in 

 introducing the red Aschersonia and the brown fungus into a grove in 

 Orlando as long ago as 1898 or 1899. 



Dr. Berger has recorded experiments in pinning leaves infected with 

 red Aschersonia in June and July, 1906, and in spraying the spores 

 in a water solution in July and August, 1906. Results of pinning 

 leaves infected with brown fungus and of spraying water solutions 

 of brown-fungus mycelium incidental to experiments with red Ascher- 

 sonia have also been noted by the same author. Dr. Berger was the 

 first experimenter to obtain results in spraying water mixtures of the 

 spores, justifying the use of this method in preference to the tree- 

 planting method or leaf-pinning method. He was also the first to 

 recommend that the spraying method be used to spread red and 

 yellow Aschersonias in groves already infected in order to aid arti- 

 ficially in their multiplication and in the increasing of their efficacy. 



EXPERIMENTAL METHODS. 



In connection with the present investigations extensive experi- 

 mental work has been conducted to determine the best methods and 

 most favorable conditions for introducing the fungous parasites into 

 groves where they do not exist, as well as to determine to what extent 

 practical benefit can be derived through artificial methods of spread 

 and encouragement of the growth of these fungi in groves where they 

 already are present and well distributed. During 1906, 1907, and 

 1908 a total of about 3,500 trees was included in the experimental 

 work. In addition, fully as many trees sprayed with water mixture 

 of spores by citrus growers as independent experiments have been 

 carefuUy examined and extensive data concerning the results obtained. 



» Bui. 67, Fla. Agr. Exp. Sta., pp. 624-625, 1903. 



