How to deal with hollyhock rust
HOLLYHOCK rust has struck for the second year running, but I’m hoping that this year I’ve caught it early enough to prevent it spreading to healthy plants and weakening the affected ones to the extent they need to be removed and destroyed.
This is a fungal disease caused by Puccinia malvacearum and is spread via airborne spores. The symptoms are bright orange or yellow spots on the leaf surface, lumpy pustules under the leaves, and spots and pustules developing on the stems. In severe cases the leaves shrivel and fall, and the plant loses vigour and becomes stunted. Controlling it isn’t easy, but isn’t impossible, either. Cut off all affected leaves and either burn or bin them. Don’t add them to the compost heap, and sterilise secateurs afterwards.
Keep plants well watered and avoid dense planting as this will restrict airflow. Try not to grow related plants such as lavatera, hibiscus and abutilon if hollyhocks feature in your garden. Dispose of affected plants and don’t keep the seed from rusted plants for future use. Check that plants bought in from elsewhere are free of the problem. In severe cases use a fungicide such as Bayer Fungus Fighter Plus and Scotts Fungus Clear Ultra.
Remove and destroy hollyhock leaves as soon as they show signs of rust
Fungicide can help control the problem