 |
The Gardener's Almanac |  |
||||
| Index | FAQ's | Links | Photos | Guest book | ||
| Rose Blackspot |
|
|
|
Blackspot is a serious disease that affects many types of roses in particular hybrid teas, floribundas and climbers.
Some modern cultivars show some resistance to this disease, and some older cultivars are not affected at all, so when buying plants this is worth considering.
The disease is caused by a fungus that spends its winter in fallen leaves.
It can also over-winter on green stems and in buds.
The over-wintered spores are spread by wind and rain onto emerging young leaves in spring.
The disease is recognized as dark, spreading spots on the upper leaf surface sometimes surrounded by a yellow zone.
During development, the black lesions spread, and more spores are released to be spread by rain to form new infections.
This produces premature leaf fall which in turn weakens the plant, and reduces flower numbers
To control the disease, hard prune after flowering, and remove fallen leaves.
Annual pruning done in spring will hopefully deal with any remaining spores.
Destroy the prunings and fallen leaves, do not compost them.
Fungicides are available to control this disease, check with your local garden center.
About this Site © The Gardener's Almanac 2005 Top of page