April, '12] WATSON: FUNGI AS INSECTICIDES 201 



very efficient enemy of the San Jose Scale and worked out a method 

 of artificially aiding its dissemination by tying on to the branches of 

 infested trees where the fungus was absent, small twigs on which 

 were scales infested with fungi, and also a method of spraying into 

 the trees water containing the spores obtained from cultures of the 

 fungus in artificial media. 



Prof. H. A. Gossard (Bull. 67) took up the artificial spreading of the 

 fungi parasitizing whitefly. Following Webber he recommended the 

 method of transplanting nursery stock on which were parasitized 

 larvse. 



The method which is now exclusively used on a commercial scale 

 has been developed by Dr. E. W. Berger (Bulls. 88, 97, and 103, Fla. 

 Exp. Sta. and Annual Reports 1907-11). It is to spray into the 

 tiees water in which are held suspended the spores and mycelia of 

 the fungi. He found that the spores from about 40 fungus pustules 

 to one pint of water was sufficient and that the leaves may be kept 

 six months or more in cold storage, thus obviating one frequent diffi- 

 culty, that of finding fungous material in the spring and early summer 

 following the dry season. Or fungi may be used which have been 

 grown on sweet-potato or other artificial media. 



Prof. H. S. FawTett, Plant Pathologist of the station, and Director 

 P. H. Rolfs have worked on the life-histories of the fungi concerned and 

 the methods of their propagation on artificial media (Bulls. 41 and 

 94 and Univ. Fla. Special Studies No. 1, 1908, Mycologia II-4, 1910). 



Scales. The scale which is most widespread and has received the 

 most attention lately is the citrus Purple Scale {Lepidosaphes beckii) 

 and the following remarks apply chiefly to it, although many others 

 seem to be affected to about the same degree. The chief fungi con- 

 cerned are, the Red-Headed {Sphcerostilbe coccophila), the Black 

 Fungus {Myriangium duricei), and the White-headed {Ophionectria 

 cocci cola) . 



It is not the object of this paper to go fully into the historical aspects 

 of this subject as that has been done elsewhere (Berger Rep. of Fla. 

 Hort. Soc. 1911), but it is well in passing to call attention to the 

 fact that when this scale was first introduced and before the fungi 

 had commenced to be effective, it was regarded as a much more serious 

 pest than is now the case. So serious indeed that the very existence 

 of the citrus industry seemed to be threatened. Even with no atten- 

 tion on the part of the grower and no efforts to aid in their dissemina- 

 tion, the fungi are very efficient aids in holding the scale in check. To 

 what an extent this is true can be seen from the accompanying table 

 (Table I) in the column showing the effect of spraying with Bordeaux 

 mixture. It has long been recognized that spraying with this standard 



