PATHOGENIC COMPARISON OF ERWINIA CHRYSANTHEMI STRAINS FROM PINEAPPLE WITH STRAINS FROM OTHER HOSTS

W.H. LIM and P.H. LOWINGS

SUMMARY

Pathogenicity of seven Erwinia chrysanthemi strains from pineapple was compared with the pathogenicity of 24 strains from 17 other hosts using maize, pineapple, chrysanthemum and potato as test plants. On detached pineapple leaves, the pineapple strains and seven non-pineapple strains from maize, Philodendron, Syngonium and Begonia induced soft rotting at the base of the leaves. On pineapple fruits, however, only the pineapple strain was able to cause extensive soft rot, typical of fruit collapse. The pineapple strain is distinct from all the other strains tested and should be distinguished from them by designating the name E. chrysanthemi (pineapple strain). Many isolates which were inoculated onto maize by the whorl inoculation method (with Tween 40) produced positive symptoms, indicating the unsuitability of this method for distinguishing strains. Mature chrysantemums are good test plants to distinguish the chrysanthemum strains from maize, pineapple, sugarcane, potato and several others.

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