PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 67 
than vice versa, thus giving more live insects to those trees upon which 
the fungus spread best than they otherwise would have had. This, 
however, was an advantage so far as the increase in the average number 
of fungous pustules per leaf was concerned. On the other hand, the 
experimental block, which was heavily infested at the beginning of the 
season, began blackening by the 1st of June, and this heavy infestation 
would unquestionably have continued and a general blackening have 
resulted in spite of an increase in the number of fungous pustules to 21 
or even 25 per leaf. From our data in this experiment and from our 
general knowledge of white-fly and fungous conditions, we conclude 
that no practical benefit to the orange trees resulted during 1909 from 
the repeated attempts to spread the infection of red fungus, and that 
from tins standpoint the results would not have been affected if the 
trees of series A had been isolated. The only accomplishment of 
practical importance was in the introduction of the red fungus onto 
trees not previously infected. 
(4) Wills Grove, Sutherland, Fla. Grapefruit trees infested by cloudy- 
winged white fly only. — In cooperative experimental work, in 1909, 
Mr. F. L Wills, of Sutherland, Fla., sprayed 49 trees in the middle 
of a block of 378 trees, all heavily infested with the cloudy-winged 
white fly, and already slightly infected with yellow Aschersonia, 
with mixture of yellow Aschersonia on May 18, June 11, July 8, 
August 9, and after the 1st of September until October 18 one-half 
of the sprayed trees every two weeks, the rest once a month. By 
July 17 a count of 185 leaves, picked promiscuously, showed that 
173 were infected, with an average of 41 pustules per leaf, or nearly 
twice as many pustules as were present on leaves picked from check 
trees. On August 18 Mr. Wills noted that the fungus was spreading 
very rapidly and making its appearance over 20 acres of orange and 
tangerine trees adjoining. At the time there was an average of 90.7 
pustules per leaf on the sprayed trees as compared with 51.8 pus- 
tules on the check trees. By September 22 a count of 200 leaves 
from the sprayed and from the unsprayed check trees showed the 
average abundance of pustules per leaf to be 118.4 and 137.5, re- 
spectively; in other words, by the middle of September, the natural 
spread in the entire block had been so rapid that there was moro 
fungus in the check than in the sprayed tree. By the middle of 
November no difference could be noted on a general examination of the 
grove, and both the owner and the authors concluded that had no 
spraying been done the natural spread would have accomplished the 
same results. 
(5) Fairbanks Grove, Island Grove, Fla. — Orange trees infected with 
citrus white fly only; cooperative experiments arranged with Rev. 
J. J. Glass. — The trees were fairly heavily infested and there was a 
