In August 1946, marked viruslike symptoms were observed on watermelon {Citrullus vulgaris Schrad.) and muskmelon (Cucumis melo L.) plants in a field at Merrimac, Wis. Inoculations from infected plants to tobacco (Nicotiana tabacum L.), cucumber (Cucumis sativus i.)> ö.nd watermelon demonstrated that the disease was of virus origin. Isolates from watermelon and muskmelon were identical, and one ...