Cucumber green mottle mosaic virus
Cucumber green mottle mosaic virus (CGMMV) is an exotic plant disease, not considered to be established in South Australia.
Background
CGMMV occurs in Europe, Asia, the Middle East, and some parts of the USA and Canada.
It was found in Australia on melon crops in 2014, first detected in the Northern Territory, then in Queensland. CGMMV has since been reported on cucumber crops in Western Australia, Queensland, and in the northern Adelaide Plains of SA.
Biosecurity SA has worked with the affected property owners to contain the disease.
Impacts
CGMMV infects fruit, vegetables and weeds belonging to the family Cucurbitaceae. The most common targets are watermelon, cucumber, melons, zucchini, pumpkin, squash, bitter gourd, and bottle gourd.
The virus can spread easily and stay alive for extended periods in plant debris and soil. It can result in substantial crop losses.
CGMMV does not pose any risk to human health.
Management
Management
There is no known cure for CGMMV – preventing infection is the key to protecting your crops.
The virus can remain dormant within the seed coat and enters the plant through wounds. It can spread through:
- root contact of plants in contaminated soil
- water or nutrient solutions in soil-less culture
- protected or high-input culture systems where plants are pruned, staked, handled or touched
- clothing, or the hands of people who have come in contact with infected plants
- packaging materials such as bins used for harvesting, storage or marketing fruit – avoid recycling these materials
- field production by machinery, pickers, and possibly birds, bees and other wildlife in the crop
- infected rootstock plants and grafts
- seed harvested from infected plants.
The risk of spreading CGMMV onto farms arises when moving propagation material and equipment between properties and regions. Make sure you follow biosecurity measures to control CGMMV.
Identification
Symptoms of CGMMV vary between plant species. With at least 5 strains of the virus, it is difficult to diagnose without laboratory testing.
CGMMV may be indistinct in young seedlings. In severe infections, embryonic leaves may become yellow. The signs of CGMMV on mature leaves are:
- mottling and mosaic patterns
- turning pale or yellow-white
- blistering or bubbling
- vein clearing
- leaf distortion.
There are often no external symptoms on fruit, however it can show as:
- spotted or streaked and distorted, especially during high temperatures
- internally discoloured and rotting
- uneven ripening.
