Abstract
The effect of root-dipping, banding, and spraying with antiviral substances such as blasticidin S (BcS), ohyamycin (OM), polyoxin A (PO A), and thiouracil (2-TU), upon systemic and local infections of tomato seedlings inoculated with tobacco mosaic virus (TMV) and/or potato virus X (PVX) was studied. A preinoculation root-dipping plus postinoculation banding and spraying reduced the percentage of infection, prolonged the incubation period, and decreased the virus concentration in roots. OM showed the most distinct virus-inhibition, but the root elongation as well as shoot growth was inhibited by OM of 100ppm. BcS of 0.5-1.0ppm and 2-TU of 25-50ppm reduced the severity of symptoms and decreased the virus concentration without apparent toxicities to the plants. Methods for reducing the phytotoxicity caused by these chemicals were tested. It was found that manganese ion, when mixed with BcS or OM, reduced the toxicity due to the antibiotics, especially as judged by a recovery from the retarded root growth. Manganese did not affect so much the virus-inhibition by BcS.
