ARTIFTCTATJ.Y SPREADINf! FUNCOUS DISEASES. 47 



rations. An oxaiiiination of 100 IcaA-cs ])ick(Ml at random in 5 ty])ioal 

 groves in Alanatoo County and 5 in Loo County in January, 1009, 

 showed a ratio of 14 rod-fungus pustules to 32 brown-fungus pustules 

 in grov(>s wliicli liatl all bo<Mi infoctod witli botli s])o('ios for several 

 years previous. In 9 of the 10 groves the total number of ])ustules 

 of brown fungus counted exceeded the total number of red-fungus 

 ])ustulos. The isinglo oxce])tion was a grov(^ in wliich both species of 

 fungous })arasites were present in almost negligibhi amounts. In 

 Orange County the brown fungus has also as a rule shown greater nat- 

 ural eflicaey tlian the rod whoroA'er the two sj)eeies have both boon pres- 

 ent in the same grove and both have become well established. For 

 example, in grove No. 1 of Tables II and IX the average number of 

 i<>d and brown fungus pustules ])or leaf was found to be 9.9 and 14.5, 

 respectively, in December, 1909, and 3.7 and 52.9 in December, 1910. 

 The natural efficacy of the yellow fungus against the cloudy-winged 

 white fly is about the same, according to the; authors' observations, 

 as the natural ellicacy of tlie red fungus against the citrus white fly. 

 The fact that tlie red and brown fungi have shown very little adapta- 

 bility to the cloudy-^^^nged species has been mentioned elsewhere. 



HAVE THE FUNGOUS PARASITES 1^•CREARE^^ IN NATURAL EFFICACY SINCE THEIR FIRST 



DISCOVERY? 



The statement sometimes heartl to the effect that the fungous dis- 

 eases are more effective now than formerly is unquestionably ^\^thout 

 the slightest foundation, and it is unnecessary to devote any space 

 to a discussion of the subject. 



ARTIFICIAL MEANS OF SPREADING FUNGOUS DISEASES. 



HISTORY OF WORK IN THIS LINE. 



Dr. H. J. Webber, who first discovered the red Aschersonia and 

 the brown wliite-fly fungus, was also the first to undertake experi- 

 ments A\ath artificial metliods of spread .^ The methods tested included 

 mixing the spores of the Aschersonia \Wth water and spraying the 

 infested leaves with an atomizer, hanging branches with pustules of 

 the Aschersonia and brown wliite-flj^ fungus above branches in- 

 fested with the white fly in groves where the fungous parasites did 

 not occur, and transplanting young trees with parasitized white flies. 

 The first method is reported to have failed to give satisfactory results. 

 The second method was tested several times, but results were obtained 

 in only one instance in the case of the red Aschersonia and once in 

 the case of the brown fungus. The season of the year when these 

 tests were made is not stated. The transplanting of young trees 

 seemed the most reliable method, and this was recommended in estab- 



1 Bui. 13, Div. Veg. Phys. and Path., U. S. Dept. Agr., pp. 26 and 30, 1897. 



