66 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



experiments were conducted with the view to showdng the effect of 

 applying spores brought nearly to the point of germination in this 

 medium. In this and other series of experiments the solutions were 

 applied under favorable weather conditions, but no difTerence could 

 be observed between the infection secured with nutrient solution 

 and ordinary solutions used as checks. In some instances better 

 infections were secured where no nutrient was added. Similar 

 experiments with glucose as the nutrient have been reported by 

 Dr. E. W. Berger ^ who also obtained negative results. 



Effect of sulphur waters on spores. — Experiments to determine 

 what effect sulphur water has upon securing infections with water 

 solutions of spores have been conducted only in the grove. Artesian 

 water from Manatee County was used. An equal number of red 

 Aschersonia pustules (400) were soaked in sulphur water and in lake 

 water for one-half hour, shaken thoroughly, and the solutions used for 

 dipping on June 25, 1909. By July 10, on the six shoots dipped in 

 sulphur-water solution, representing an aggregate of 54 leaves, 180 

 pustules had developed, while on the four shoots dipped in lake- 

 water solution with a total of 28 leaves, 89 pustules developed. For 

 each solution 3.3 and 3.2 pustules per leaf , respectively, were obtained. 

 Check shoots developed no fungus. The results obtained gave no 

 evidence of any injurious effect of the sulphur water on the spores of 

 the fungus. 



LENGTH OF VITALITY OF SPORES. 



Field tests only have been made by the authors in determining 

 the length of vitality of spores of white-ily fungi. No definite infec- 

 tions resulted from the use of fungi, either the Aschersonias or the 

 brown fungus, collected from September to December, 1907, and 

 applied in various ways during the following summer months. Infec- 

 tions were secured with fungus dropped by the cold in January, 

 1906, during the following June, although far better infections at the 

 same time followed the use from freshly picked fungus, as a check. 

 In all, the authors have used in their experiments about a barrel of 

 fungus-infected leaves, collected during the early winter months, with- 

 out success. In several instances a very minute infection, one or two 

 })ustules, was detected, but under such conditions that it was more 

 than probable that the infection came from other sources. Special 

 attention has been given to these experiments in order to determine 

 the value of picldng fungus-infected leaves in the fall so that much of 

 the fungus that falls from the leaves during the winter months might 

 be saved for spring infections. The results above mentioned would 

 indicate that such fungus pustules are valueless unless some more 

 successful method be devised for preserving the fungus-infected 



1 Kept. Fla. Agr. Exp. Sta. for year ending June 30, 1908, p. 111. 



