PRACTICABILITY OF INCREASING EFFICACY OF FUNGI. 07 



tliaii vi '0 versa, tlius t::ivin<:; nunv livo insects lo those trees iij>()n whicli 

 the fuii.i2;us sj^reiul l)est than tliev otherAvise would liave liad. Tliis, 

 lioAvever, was an advanta<]:c so far as tlie increase in tlie average minibcr 

 of fungous pustules per leaf was concerned. On the otlier liand, the 

 expeiimental block, which was heavily infested at the beginning of the 

 season, began blackening by tlie 1st of June, and tliis heavy infestation 

 Avould unquestionably liave continued and a general blackening liave 

 resulted in spite of an increase in the number of fungous pustides to 21 

 or even 25 per leaf. From our data in tliis experiment and froju our 

 general knowledge of white-fly and fungous conditions, we conclude 

 that no practical benefit to the orange trees resulted during 190!) froju 

 the repeated attempts to spread tlie infection of red fungus, and tliat 

 from tliis standpoint the results would not have been affected if tlie 

 trees of series A had been isolated. Tlie onh' accomplishment of 

 practical inn)ortance was in the introduction of the retl fungus onto 

 trees not previously infected. 



(4) Wills Grove, Sutherland, Fla. Grapefruit trees infested hy cloudy- 

 winged v:liite fiy only. — In cooperative experiniental work, in 1909, 

 ]\fr. F. L Wills, of Sutherland, Fla., sprayed 49 trees in tlie middle 

 of a block of 378 trees, all heavily infested with the cloudy-winged 

 white fly, and already slightly infected with yellow Aschersonia, 

 Mith mixture of yellow Aschersonia on May 18, June 11, Julv 8, 

 August 9, and after the 1st of September until October 18 one-lialf 

 of the sprayed trees every two weeks, the rest once a month. By 

 Juh' 17 a count of 185 leaves, picked promiscuously, showed that 

 173 were infected, with an average of 41 pustules per leaf, or nearly 

 tw^ce as many pustides 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 })us- 

 tules on the check trees. B}' September 22 a count of 200 leaves 

 from the sprayed and from the unsprayed check trees showed tlie 

 average abundance of pustules per leaf to be 118.4 and 137.5, re- 

 spectively; in otJier words, b}' the middle of September, the natiual 

 spread in the entire block had been so rapid that there was moi"C 

 fungus in the check than in the sprayed tree. By the jniddle of 

 November no difference could be noted on a general examination of tlie 

 grove, and both the owner and tlie authoi-s concluded that luid no 

 spraying been done the natural spread would liave accomphshed the 

 same results. 



(5) FairhanJcs Grove, Island Grove, Fla. — Orange trees infected with 

 citrus white fiy only; cooperative experiments arranged with Rev'. 

 J . J . Glass. — Tlie trees were fairlv heavilv infested and there was a 



