ANTAGONISM OF BACTERIA TO AGROBACTERIUM-T UMEFACIENS

In order to test the efficiency of bacteria for controling Agrobacteri um tumefaciens, plants of Bryophyllum calycimum had roots and collar i mmersed for 20 minutes in the suspensions of nine actinomycetes, six i solates of fluorescent Pseudomonas spp. and one isolate of Bacillus su btilis. After 24 and 48 h plants were inoculated in the collar region by wounding with a needle. The evaluation was made 15 d after inoculat ion when gall symptoms were clearly evidenced. The parameters evaluate d were presence of galls and gall weight. In the first experiment none of the actinomycetes reduced disease incidence or severity. Isolates 10124 and 10574 presented toxicity to the host, inducing plant death. In the second experiment some bacterial isolates reduced disease sever ity in relation to gall weight varying from 40 to 70%. The antagonism of the bacterial isolates against the pathogen could not be detected ' 'in vitro''. The studies of bacterial sensitivity to antibiotics and f ungicides revealed that isolate C21 was inhibited by mancozeb, kasugam ycin and oxytetracycline + streptomycin, as well as P2 was affected by oxytetracycline + streptomycin.