VIRUS DISEASES OF PAPAYA A. A. Cook1 Introduction Papaya (Carica papaya L.) (13)2 is widely grown in trop- ica' and semi-tropical latitudes for the edible fruit with delicate taste. The extensive adaptation of this plant and wide accept- ance of the fruit offer considerable promise for papaya as a commercial crop for local and export purposes. Virus diseases of papaya have been reported from nearly every continent where the crop is grown, and, in many areas, severely restrict profitable production. Early publications re- lating tu these diseases emphasize descriptions of symptoms observed on naturally infected plants and the common names applied to them by the investigators. Partly because of geo- graphic separation, a concerted study and comparison of the diseases from different areas has not been made. Confusion ,about the identity and diagnostic characteristics of specific diseases has arisen because of different environmental condi- tions, disease descriptions from varieties of unknown or un- related pedigrees, and/or information relative to inconsistent aspects of syndromes or causes. A review of existing information about virus diseases of papaya and related observations of investigators was published in 1949 (39). A number of reports since then have contributed significantly to identification of some of the diseases and causal viruses. Some of these recent publications were mentioned in the review of Frossard (28). It is unfortunate that the term "mosaic" has been used both to describe a type of symptom associated with more than one disease as well as the common name for a single disease caused by a distinct, infectious entity. Identification of diseases from symptoms alone can be quite misleading because of the simi- larity of syndromes induced by different viruses. In this resume an attempt was made to relate virus diseases of papaya, pre- viously described under various names, according to definite characteristics: i.e., transmissibility by insects, distinctive visi- ble symptoms (latex flow), virus particle morphology, phys- 1Professor (Plant Pathologist), Department of Plant Pathology, Univer- sity of Florida, IFAS, Gainesville, Florida, 32601. 2Numbers in parentheses refer to Literature Cited.