PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 61 



attempting materially to increase the efficacy of fimgous parasites by 

 artilicially increasing the Immiility. Even were it p()ssi])le to secnre 

 a high percentage of liumiility on high pine land in the counties 

 mentioned and in the interior of the peninsula comparing favorably 

 witli the humidity in the most humid hammock lands, the accom- 

 plishment Avoidd avail nothing of j)ractical importance.' If the con- 

 ditions in these very hammock lands of Lee and Manatee counties 

 were imj)roved so that the work of the fungous parasites were suffi- 

 cient to keep the cro]) of fruit free of sooty mold one year in two 

 instead of, as at present, one year in tliree, the injury from the 

 white fly would still be sufficient to demand more satisfactory means 

 of control than natural enemies afford. Notwithstanding the appar- 

 ently self-evident impracticability of efforts in this line, the careful 

 investigation of the subject would be of much mterest and possibly 

 of usefulness in comicction with the investigation of other fungous 

 parasites affecting msect pests. In a small investigation conducted 

 within reasonable time limit, however, the elimination of unpromis- 

 ing lines is necessary. 



, INCREASING THE EFFICACY BY SPKEADING THE INFECTIONS. 



The most important subject in connection with the investigation 

 of white-fly fungous parasites is that of increasing their efficacy by 

 artificially spreading the mfection. At the time of this writing the 

 only i)ublished record of the results secured by an attemj^t to spread 

 infections where the fungous parasites already exist, and properly 

 classifiable as a residt of this land, has been made by Dr. Berger.- 



The authors' held investigations of tliis subject consist of person- 

 ally conducted or cooperative experimental work in six groves in 

 addition to more general observations in a few other groves where 

 work in this line was taken uj) commercially. Altogether more than 

 1,500 trees were included in the experimental blocks in these groves, 

 not including the untreated trees left as checks. 



(1) Gettysharg Grove, near Orlando, Fla. Estimated 94-S per cent 

 citrus white jly, 5.2 per cent cloudy^winged lohite fly. — To determine 

 what effect one introduction of spoies of the red Aschersonia might 

 have on the abundance of fungus in a grove already slightly infected, 



» Since the preparation of this report the investigation by Prof. 11. S. Fawcett, of the Fla. Agric. 

 Exp. Sta., of a new disease of citrus fruits, known as "stem and rot" (Fla. Exp. Sta. Bui. 107, 1911), 

 has shown that humid conditions in oranpc groves which are considered an advantage in favoring the 

 white fly parasitic fungi are a serious disadvantage in also favoring the destructive disease of the fruit. 



«Ropt. Fla. Agr. Exp. Sta. for fiscal your ending June -iO, V.m, p. xli. "On .Vug. 17, 1900, red fungus 

 was reintroduced into 5ix trees in the Heathevat grove in order to compare, at a later date, the amount of 

 fungus in these trees with those not treated again. On Mar. 2, 1909, these trees were estunated by Mr. 

 Jos. E. Kilgore and the Entomologist to have 10 times as nuidi fungus in them as six trees in either 

 row next to them, showing clearly that fungus should be introduced frequently, if necessary to get the 

 best results." 



