STUDIES ON BACTERIAL STALK-ROT DISEASE OF MAIZE

Abstract

I- Disease survey in 1996- I 997 indicated that a bacterial stalk rot disease was spreading in the maize growing fields of 5 governorates of lower Egypt. Infection percentage ranged from 0.72 in Menufiya to I .75 in Kafr EI-Sheikh.

2- A number of I 00 isolates were recovered from affected maize plants in 1996. Twenty four isolates, out of them were selected for fUJiher studies. 3- Whereas, twelve of the 24 isolated cultures proved to be pathogenic to maize, the rest of isolates were non-pathogenic. 4- Three of these parthogenic isolates along with two of the non­ pathogenic were studied for their virulence to 6 maize inbred lines in order to confirm the obtained results. It was found that virulence was correlated only with the pathogenic ones. 5- Cultural, biochemical and physiological study of the 12 isolates indicated that they did not differ from each other. They agreed in their characters with the reference cultures (obtained from the American type culture collection) indicating the probability of being strains of Erwinia cluysanthemi. 6- Dot-immunobinding assay (DIA) for the pathogen isolates showed that each one IS similar to the others and to the reference cultures where they gave positive reaction with antisera of the American cultures.