Over the past several years, the canna’s rise in popularity among the gardening community and international plant exchanges has simultaneously led to an increase in the incidence of bean yellow mosaic virus, canna yellow streak virus and canna yellow mottle virus. This is a serious concern due to the canna’s prominent role in our gardens and conservatories.
To tackle this issue, we are developing new cultivars from seeds collected from virus-free plants in our collection and refining a protocol for micropropagation of canna’s using shoot-tip cultures from virus-free stock. We are also improving our management of stock plants by:
Rotating field locations so that stock are never in the same spot for at least three years
Spacing plants further apart so that virus can’t pass from root to root
Eliminating tillage between stock rows to prevent mechanical virus transmission
Removing symptomatic plants from stock rows
Growing seedlings in the greenhouse to protect them from insects that may spread virus
Increasing plant testing
Additionally, our researchers are working to develop a protocol for using meristem culture to recover virus-free plants from infected stock. We were the first to apply this difficult process to the canna and endured several failed attempts before a student in the Longwood Graduate Program successfully recovered a virus-free canna using meristem culture with heat treatments.