Effect of Injected Antiviral Compounds on Apple Mosaic, Scar Skin, and Dapple Apple Diseases of Apple Trees. Susan M. Cheplick, Former Graduate Research Assistant, Department of Plant Pathology, University of Massachusetts, Amherst 01003. G. N. Agrios, Professor, Department of Plant Pathology, University of Massachusetts, Amherst 01003. Plant Dis. 67:1130-1133. Accepted for publication 18 April 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1130.

Several synthetic chemicals with known antiviral or antibiotic activity were injected under pressure into apple trees showing symptoms of apple mosaic, scar skin, or dapple apple. Compounds included ribavirin, 2-thiouracil, formycin B, amantadine HCl, methisazone, and oxytetracycline. Ribavirin completely suppressed symptom expression when injected during autumn into orchard trees and greenhouse-grown grafts infected with apple mosaic virus (AMV). Similar injections of oxytetracycline significantly increased the frequency and enhanced the severity of foliar symptoms. Injections of ribavirin in the spring reduced symptom expression but did not completely control AMV infection in orchard trees, whereas injections of oxytetracycline in the spring did not affect foliar symptom expression. The other compounds had little or no effect on apple mosaic symptoms. Injections of the antiviral compounds into orchard trees showing symptoms of scar skin or dapple apple disease and direct application to the fruit of trees with dapple apple disease did not produce significant changes in fruit symptoms.