Suppression of Sumatra disease symptoms in cloves treated with antibiotics

Repeated infusions of a mixture of oxytetracycline and streptomycin into the wood of initially symptomless clove trees exposed to natural infection by Sumatra disease resulted in a delay in symptom onset and slower rates of symptom development compared with untreated trees. The numbers of bacterially occluded vessels in root samples of treated trees were significantly fewer than those from controls. These results strongly support the hypothesis that a xylem‐limited. Gram‐negative bacterium, known to be consistently associated with Sumatra disease symptoms, is the causal agent. The productive life of treated trees was usefully extended but some phytotoxicity was observed, resulting in leaf scorching and stunted flower buds. In view of the high value of the crop, antibiotic therapy merits further investigation as a short‐term control measure.