Controlling Virus Diseases in Major International Flower and Bulb Crops. Roger H. Lawson, U.S. Department of Agriculture, Beltsville, MD. Plant Dis. 65:780. . This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-780.