August Pest of the Month: Cucumber mosaic virus

Cucumber mosaic virus (CMV) infects hundreds of host plants including vegetables, ornamental, grain and weed species. It is also known to infect certain specialty plants causing problems for collectors, e.g. Adeniums. It is spread by aphids feeding on infected plants followed by healthy plants. It takes less than one minute for aphids to acquire the virus and they can immediately spread it to all healthy plants for several hours. It is also spread by propagation material and may also when handling and trimming infected plants followed by healthy plants.

Symptoms include yellow mosaic patterns on leaves, deformed stunted foliage (cupping and puckering etc), stunting of entire plants and sometimes chlorotic ringspots. Once infected, plants cannot be cured. Management involves hygienic removal of infected plants from the production area, discard in covered bins prior to removal from the site. If aphids are present, take care to stop their spread before handling plants, which may be achieved with an appropriate pesticide.

If you believe you have plants infected with CMV or other viruses it is recommended to get advice prior to testing; many plants will display non-pathogenic disorders that are superficially similar to those caused by CMV and other viruses. Send pictures of symptomatic plants to a diagnostic laboratory with plant virologists, e.g. Grow Help. They can assist you to determine if further testing is warranted and complete testing where required. All production nurseries receive testing of 6 free samples through the diagnostic service, Grow Help Australia.

For more information refer to the CMV in Adeniums factsheet, virus management factsheet and the webinar on virus identification and management.

 

Figure caption: Varied leaf symptoms of Calendula infected with Cucumber mosaic virus.