INDUCED RESISTANCE IN APPLE AND PEAR SEEDLINGS TO FIRE BLIGHT BY BION® AND CORRELATION WITH SOME DEFENSE-RELATED ENZYMES.

Apple and Pear seedlings were treated with foliar applications of the chemical agent benzo [1,2,3] thiadiazole-7-carbothioic acid-S-methyl ester (BTH), the active ingredient in the Novartis plant activator Bion®, to induce systemic acquired resistance to fire blight caused by Erwinia amylovora. Seedlings were treated with BTH, several days prior to inoculation by wounding a single, young leaf and spraying 10⁶ to 10⁸ CFU/ml of E. amylovora over the entire surface of the plants.
Control by BTH was usually equal to or better than streptomycin on apple seedlings but not as effective as streptomycin on pear seedlings.
The best timing for induction of resistance was 2 and 4 days prior to inoculation.
BTH rates of 100–400 mg/l were effective and in some trials, a rate effect was observed as concentrations increased.
Evidence for induced resistance was indicated by enhanced activities of the defense-related peroxidase and glutathione-S-transferase enzymes in those plants protected with BTH but not in the untreated plants.

VIII International Workshop on Fire Blight

S.V. Thomson, M.N. Brisset, R. Chartier, J.P. Paulin

Erwinia amylovora, systemic acquired resistance

https://doi.org/10.17660/ActaHortic.1999.489.101