46 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



thoroughly oiackened as any to be found in the State and in 1908 

 was only slightly improved. In Lee County the hammock groves 

 located near the Caloosahatchee and Orange Rivers have been much 

 less uniform than hammock groves in Manatee Coimty as regards the 

 efficacy of the fungous parasites. It has been more frequent to find 

 very effective work by the fungi in one section of a grove, while 

 another section of the same grove has been heavily infested and 

 thorouglily blackened. On the whole the average condition in these 

 groves in ]\Ianatee and Lee counties has conformed entirely to the 

 estimates given in previous publications; in effect, that the efficacy 

 of the fungi amounts to about one-third of a complete remedy. 



In the interior of the State, in high pine land groves, the natural 

 efficacy of the fungous parasites appears to be somewhat less than in 

 the hammock groves referred to. Prof. Gossard mentioned the 

 presence of the red and the brown fungi at Orlando in his annual 

 report for the year ending June, 1901.^ According to an authenti 

 report, the grove of Hon. J. M. Cheney (grove No. 3 of Table I, and 

 No. 1 of Tables II and IX) at Orlando was one of the earliest in that 

 section to become infected with the red and the brown fungi. This 

 introduction was not later than 1901. In 1907 the grove was entirely 

 free from sooty mold, as noted in the discussion of unexplained mor- 

 tality. This was the first year that the fruit had not been generally 

 blackened since the introduction of the fungi, and the fungous diseases 

 in this case were not responsible. In 1908 and 1909 the trees and 

 fruit were very black, while by the end of the latter season the insects 

 had been reduced m an entirely satisfactory manner. While we 

 have no record concerning the condition of the crop for 1910 in this 

 grove, it may be said without hesitancy that if not clean it was due 

 to the interference with the efficacy of the fungi by adult white flies 

 migrating from other groves or from China and umbrella trees. 

 Without doubt China and umbrella trees have seriously interfered 

 with the natural efficacy of the fungous parasites in Orlando and other 

 cities and towns in Florida, but at the most the natural efficacy of 

 the fungous parasites at Orlando and at similar locations apparently 

 will not equal the natural efficacy in the hammock groves of Manatee 

 and Lee counties. 



COMPARATIVE EFFICACY OF DIFFERENT SPECIES OF PARASITIC FUNGI. 



In the preceding topics, under the general heading of natural effi- 

 cacy, the brown, red, and yellow I3arasitic fungi have been discussed 

 collectively. All other species so far reported as white-fly parasites 

 are of negligible value, as shown elsewhere. The brown fungus has 

 long been considered as more effective than the red fungus against 

 the citrus white fly. Tliis estimate is in accordance with our obser- 



i Rept. Fla. Agr. Exp. Sta., p. 65, 1901. 



