• 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.

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.