Suppressive Effects of Antibiotics of Tetracycline Group on Symptom Development of Mulberry Dwarf Disease

Abstract

Doi et al. (1967) have demonstrated the consistent association of Mycoplasma- or PLT group-like organisms in the phloem tissue of dwarf diseased mulberry plant. If these organisms proved to be sensitive to tetracyclines, still more evidence for an etiologic relation will be added. Accordingly, effects of chlortetracycline hydrochloride (Aureomycin) and tetracycline hydrochloride (Achromycin), of the tetracycline group, and also Kanamycin were investigated upon the symptom development of dwarf disease in mulberry seedlings. Solutions of the antibiotics were applied to infected seedlings by three methods, singly or in combination: repeated foliage spraying, soil drenching at intervals of 2&3 days, and root dipping prior to planting.
Generally, Achromycin and Aureomycin at a concentration of 100ppm showed remarkable effects in suppressing symptom development, whereas Kanamycin did not. Therapeutic effectiveness obtained by root dipping was superior to that of foliage spraying. There was no noticeable effect in the case of soil drenching. The plants recovered by treatment with these antibiotics, however, tended to develop symptoms again some period after the application was discontinued. The length of the period until re-appearance of symptoms seemed to vary with the original disease severity, the size of the seedlings, and environmental conditions. These results may indicate that mulberry dwarf disease is caused by an agent whose multiplication is inhibited by an antibiotic such as chlortetracycline and tetracycline.