Biological Studies on Bacteria Pathogenic to Melons

Abstract

SUMMARY : The study of bacterial diseases of melon plants in different localities of Egypt revealed that there are two main pathogens responsible for spotting, wilting, and rotting of the fruits. They are E. carotovora (Jones) Holland var. carotovora Dye, causing wilting and soft rotting of the fruits, and E. carotovora (Jones) Holland f. citrullis Sizova, causing spotting, wilting, and rotting of the fruits. These two pathogens caused great damage to the melon crop, where, in some instances, wilting reached 75%. Identification of these two pathogens was confirmed by comparing their biological and biochemical characteristics with certified isolates offered by the Ministry of Agriculture, Egypt, and isolate 777a (Saleh, 1977), as well as by the records reported in Bergey's Manual of Determinative Bacteriology Storage of E. carotovora var. carotovora for 3 years did not affect its virulence. It could cause wilting and rotting within 24–48 hours after inoculation. On the other hand, the virulence of B. carotovora f. citrullis was lost when kept in synthetic media for a long time The main differences between the two pathogens lie in the absence of protopectinase and tolerance of B. carotovora f. citrullis to high temperatures (47°C) compared with B. carotovora var. carotovora.