Papaya Ringspot Virus (PRV-W)

   This virus attacks all cucurbits and is the number one viral disease of cucumbers in Hawaii. Papaya Ringspot Virus Type W (PSRV-W), was previously referred to as Watermelon Mosaic Virus I. The virus also infects some weed and legume species. It produces the characteristic virus interveinal chlorosis, stunting, and misshapen fruits (Figure 3). In the field the virus is transmitted by insects, workers, and farm machinery. Greatest disease pressure is experienced during the summer months perhaps due to the increased aphid activity. The best approach to manage this disease is to use resistant cultivars. Some varieties claim resistance to PSRV-W but have not been extensively tested for disease or horticultural quality under local conditions. Insecticide applications may reduce aphid numbers in the field but this alone is usually not sufficient as a control strategy. Other practices may include the use of reflective mulches, elimination of volunteer weed hosts, and destroying cucurbit plants in nearby fields.