Progress Report on the Fungus Diseases of Scale Insects Attacking Citrus in Florida

Since 1897 when Rolfs (6) published "A Fungus Disease of the San Jose Scale," Sphxaerostilbe coccophila Tul.' and several other fungi have been credited with being of great value in controlling scale insects attacking citrus in Florida. Numerous investigators (1, 2, 7, 8, 9) following Rolfs have published papers on the efficacy of the fungus diseases; however, throughout the available literature, no one has reported seeing one of the "friendly fungi" actually growing on a living scale insect. Without evidence of the parasitism of these fungi their economic importance to the grower is in question. It has been noted by the authors that purple scale (Lepidosaphes beckii Newm.) populations often decrease very rapidly. Holloway and Young (4) have indicated that the scarcity or abundance of entomogenous fungi' has no influence on the rate of total mortality of these insects. If this be true, then some other factor must be responsible for the periodic epizootics. THE "FRIENDLY FUNGI."-The term "friendly fungi" is generally used to include the following fungi associated with scale insects, as listed by Watson and Berger (9): Red-Headed Scale Fungus (Sphaerostilbe aurantiicola (Berk. & Br.) Petch), Pink-Headed Scale Fungus (Nectria diploa Berk. & Curt.), White-Headed Scale Fungus (Podonectria coccicola (Ell. & Ev.)