Canna virus
The genus Canna is susceptible to certain plant viruses, which may result in spotted or streaked leaves, in a mild form, but can finally result in stunted growth and twisted and distorted blooms and foliage. Known species of virus are:
- Canna yellow mottle badnavirus infecting canna species.
- Bean yellow mosaic virus infecting cannas, gladiolus, freesia and many legumes.
- Tomato aspermy virus, causes mosaic in cannas, but it has not been reported affecting cannas in the UK.
- Cucumber mosaic virus, cannas are susceptible to this virus, but none found yet in England.
- Canna yellow streak virus, recently discovered by scientists at the Central Science Laboratory in England. Dr Rick Mumford, senior virologist at CSL is quoted as stating "Typical virus symptoms include flecking, mosaic, leaf streaking and necrosis, which in severe cases render plants unsaleable." The reference to this quoted article is shown below.
Known facts
Overall, very little is known about the Canna viruses, but the following points are generally accepted:- It manifests itself in rust coloured streaks or mottled markings on the leaves and in colour breaks on the flowers.
- Sometimes leaves are slightly distorted and puckered.
- Like many plants under stress, affected cannas will flower very early in the season and before the plant is full height.
- Over the years the canna will lose vigour and become increasingly unsightly.
- Some are spread by aphids and other sap sucking insects.
- At one time it was thought that Cannas may have the ability to outgrow the virus, but that is not the case.
- Most authorities advise to burn all affected cannas and start again.
- Keep any new introductions well away from potentially infected stock.