- Worldwide distribution. In Oceania, Australia, Cook Islands, FSM, Fiji, French Polynesia, Nauru, New Caledonia, Northern Mariana Islands, Tokelau, Tonga, Vanuatu. A virus of crops in the cucurbit family, and weeds.
- Damage: distortions, blisters and light and dark mosaic patterns on leaves; ring spots on the fruits merging into large dark green areas. Yields are reduced and appearance affects sales.
- Spread: aphids, and infected nursery plants. Aphids spread the virus quickly, but do not retain it for long.
- Cultural control: in nursery - check each seedling; in field - avoid overlapping crops; remove weeds and 'volunteers'; limit people entering fields; rogue disease plants; nets or floating covers; mulches to repel aphids; resistant varieties (zucchini); burn debris after harvest.
- Chemical control: insecticides not recommended, although frequent sprays of soap, white and horticultural oils may have potential.
Pacific Pests, Pathogens, Weeds & Pesticides
Watermelon - Papaya ringspot (virus-W) (392)
Papaya ringspot (virus-W)
Papaya ringspot virus-W. Previously, it was known as Watermelon mosaic virus-1. However, tests using antisera showed that it was a strain of Papaya ringspot virus. The other strain is Papaya ringspot virus-P, which infects papaya and cucurbits (see Fact Sheet no. 194). Papaya ringspot virus-W does not infect papaya.
Note, a third virus, Watermelon mosaic virus, also infects watermelon and other cucurbits; this virus causes light and dark mottling on the leaves and a slight roughening of the skin of the fruit. It was previously known as Watermelon mosaic virus-2.
AUTHOR Grahame Jackson & Mani Mua
Information from Davis RI, Ruabete TK (2010) Records of plant pathogenic viruses and virus-like agents from 22 Pacific island countries and territories: a review and an update. Australasian Plant Pathology 39, 265-291; and Papaya ringspot virus. Wikipedia. (https://en.wikipedia.org/wiki/Papaya_ringspot_virus); and from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al. CSIRO Publishing. Photo 4 former Deputy Director and Head of Agricultural Research and Information Division, MAFFF, Tonga.
Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/18: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Pacific Community.