119 



Fire "blight has a very interesting history. Burrill 

 (l88l) was the first to prove that hacteria can he the 

 cause of a plant disease and it was he (1882) who isolated 

 the causative organism of fire "blight, Micrococcus amylo - 

 vorus . For a description of the disease see Elliott (1930) 

 and Leach (19^0). Waite (I89I) was one of the first who 

 advanced experimental proof that insects were important 

 vectors of plant diseases when he showed that tees and 

 wasps were transmitters of fire "blight. 



According to Leach (19^0), fire "blight is principally 

 a disease of pears and apples although other orchard fruits 

 as well as many ornamental plants are often affected. 

 More than 90 species of plants, mostly in the family Rosa- 

 ceae, are hosts to the disease. 



The literature on this disease is contradictory as well 

 as voluminous. Concerning this state of affairs Leach 

 (19^0) states: "It is somewhat ironical that the first 

 association between insect and plant disease to "be estab- 

 lished should, after 50 years, remain in such an uncertain 

 and unsatisfactory state. " Many theories of insect trans- 

 mission have heen advanced and many insects have "been 

 incriminated, in some cases without adequate proof. 



Of the recent work on the association of this disease 

 with insects, that of Ark and Thomas (1936) seems quite 

 important. These workers have shown that Erwinia amylovora 

 may live for several days in the intestinal tract of 

 Drosophila melanogaster , Luc ilia seriata , and Musca domes - 

 tica . The eggs of Musca domestica , which, had "been laid hy 

 contaminated females, were found to harbor externally the 

 pathogen. Furthermore, hacteria fed to the larvae of 

 Drosophila melanogaster and Musca domestica persisted 

 through the puparia and could he found associated with the 

 emerging adult. 



For descriptions of Erwinia amylovora see Elliott 

 (1930) and Bergey's Manual (1939, 5th ed. , pages ^05-^06). 



Ark, P. A., and Thomas, "E. E. 1936 Persistence of 



Erwinia amylovora in certain insects. Phytopath. , 18, 



Burrill, T. J. l88l Anthrax of fruit trees; or the so- 

 called fire -"blight of pear and twig "blight of apple 

 trees. Proc. Amer. Assoc. Adv. Sci. , 2£, 583-597- 



*Burrill, T. J. 1882 The hacteria; An account of their 

 nature and effects together with a systematic descrip- 

 tion of the species. Kept. Illinois Industr. Univ., 11, 

 126, I3U. 



Elliott, C. 1930 Manual of "bacterial plant pathogens. 

 3^9 PP« Williams and Wilkins Company, Baltimore. 



