STUDY ON THE USE OF ANTIBIOTICS TO CONTROL CITRUS HUANGLUNGBIN

A study on the use of antibiotics to control citrus huanglungbin was made during the years of 1980-1983.The study involved four experiments:1)treatment of diseased citrus plants by injecting antibiotics into their trunks; 2)treatment of diseased citrus budwoods with antibiotics; 3)treatment of diseased citrus buds with antibiotics; 4)test of the efficacy time of antibiotics in the diseased citrus plant. The results obtained showed that tetracycline-HCl(1-4 million units per plant)or penici-llin-G(4-12 millions units per plant)had therapeutic effect to some extent on the disease. The symptoms of the diseased plant disappeared temporarily, but one or two years later they appeared again and even became more serious. Tetracycline-HCl distributed systematically in the diseased citrus plants after press injection and it remained only for a short duration of 20-25 days in the plant, which has been demonstrated by tissue bioassay. Treatment of diseased citrus budwoods with antibiotics showed that tctracycline-HCl(2000 ppm for 2 hrs)gave almost the same effect on the disease as hotsteam(45-47℃ for 50 min.)-No symptoms were found in the young shoots grown from the above-mentioned treated budwoods. The survival rate of budwoods treated with antibiotics was higher than that of budwoods treated with hot-steam. Of the budwoods treated with 1000 and 2000ppm of penicillin-G for 2 hrs,17.7% and 11.8% showed symptoms respectively. By treating diseased buds with 500-1000 ppm of tetracycline-HCl or penicillin-G for 30-60 min., an ideal result was obtained that no symptoms were found in the young shoots grown from the treated buds grafted on the rootstock.