INSECTS INJURIOUS TO CITRUS FRUITS 613 



early in the season before fresh fungus is available. Special di- 

 rections for this should be obtained from the State Plant Board 

 or the State Experiment Station,* (of Florida). 



The fungus is introduced into groves or trees infested with 

 whitefly but free from fungus, either by placing infected leaves 

 in and about the trees or by making a water infusion from the 

 leaves, thus forming an infusion of the spores and spraying or 

 sprinkling this on the under side of the leaves. When material is 

 scarce the infusion may be placed in a large pan or bucket and the 

 ends of a few branches of each tree dipped into this, dependence 

 for further spread being placed on the natural methods of 

 dissemination. 



The recommendation for the use of fungi states that they may 

 not always be depended upon for complete control, but that, in 

 the best practice, use should be made of them in connection with 

 the use of the contact insecticides described. 



Pure Cultures of Fungi. Of the several fungus parasites of 

 whiteflies known in Florida, two, namely, the Red Aschersonia 

 and the Yellow Aschersonia, can be readily grown in the laboratory 

 in pure cultures on sterilized sweet potato. The brown fungus 

 has also been tried, but while a vegetative growth can readily be 

 obtained it has so far refused to produce spores. The methods 

 for growing these fungi in pure cultures were perfected some years 

 ago by the Florida Experiment Station.f 



When in 1915 the State Plant Board of Florida was organized, 

 the growing of pure cultures of the Red and Yellow Aschersonias 

 became one of the projects of the Entomological Department. 

 Since that time a few hundred to as many as several thousand 

 cultures have been annually produced. A culture consists of the 

 amount of fungus and fungus spores that can be grown in a pint 

 widemouth bottle and is sufficient for starting fungus in an acre 

 grove. More or less may be used but the amount indicated has 

 been found to be quite sufficient. Sterilized plugs of sweet 

 potato were originally the medium upon which these fungi were 

 grown, but it was soon discovered that the addition of a small 



* Sse E. W. Berger, Bulletins 97 and 103, and J. R.Watson, Bulletin 123, 

 and Annual Reports for 1907 of the Entomologist and Pathologist, Fla. 

 Agr. Exp. Sta. 



fSee H. S. Fawcett, "Fungi Parasitic upon Aleyrodes citri,'' Special 

 studies No. 1, Univ. of the State of Fla., June 1908. See also, E. W. Berger, 

 p. 12, Bulletin 103, Florida Exp. Sta., 1910. 



