Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Watermelon - Papaya ringspot (virus-W) (392)

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  • 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.
Common Name

Papaya ringspot (virus-W)

Scientific Name

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. (; 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.

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