| Popis: |
The fluorescent pseudomonads associated with root and crown rots of alfalfa were divided into four groups depending on their ability to rot potato tuber slices and to elicit a typical hypersensitive reaction in tobacco leaves. The first group which rotted potato slices and was HR positive killed 38% of the alfalfa seedlings inoculated. The second group did not rot the potato slices but was HR positive. Strains of both groups were able to kill alfalfa seedlings (21 and 18%, respectively). The third group rotted potato slices but was HR negative. The last group, which did not rot potato slices or induce an HR, killed only 2% of the seedlings inoculated. A strain of Pseudomonas marginalis, 50 colonies isolated from discolored and 50 colonies isolated from normal field-grown alfalfa roots, showed that all four groups occurred, with the soft rotting-non HR group occurring in higher numbers in the discolored roots. |
