PEAC TIC ABILITY OF INCREASING EFFICACY OF FUNGI. 61 
attempting materially to increase the efficacy of fungous parasites by 
artificially increasing the humidity. Even were it possible to secure 
a high percentage of humidity on high pine land in the counties 
mentioned and in the interior of the peninsula comparing favorably 
with the humidity in the most humid hammock lands, the accom- 
plishment would avail nothing of practical importance. 1 If the con- 
ditions in these very hammock lands of Lee and Manatee counties 
were improved so that the work of the fungous parasites were suffi- 
cient to ke<3p the crop of fruit free of sooty mold one year in two 
instead of, as at present, one year in three, 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 interest and possibly 
of usefulness in connection with the investigation of other fungous 
parasites affecting insect pests. In a small investigation conducted 
within reasonable time limit, however, the elimination of unpromis- 
ing lines is necessary. 
INCREASING THE EFFICACY BY SPREADING 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 infection. At the time of this writing the 
only published record of the results secured by an attempt to spread 
infections where the fungous parasites already exist, and properly 
classifiable as a result of this kind, has been made by Dr. Berger. 2 
The authors' field investigations of this 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 up 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) Gettysburg Grove, near Orlando, Fla. Estimated 9^.8 per cent 
citrus white fly, 5.2 per cent cloudy-winged white fly. — To determine 
what effect one introduction of spores of the red Aschersonia might 
have on the abundance of fungus in a grove already slightly infected, 
i Since the preparation of this report the investigation by Prof. H. 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 orange 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. 
2 Rept. Fla. Agr. Exp. Sta. for fiscal year ending June 30, 1909, p. xli. "On Aug. 17, 1909, red fungus 
was reintroduced into six 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 estimated by Mr. 
Jos. E. Kilgore and the Entomologist to have 10 times as much 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." 
