There aren't many diseases that can afflict hollyhocks, but mallow rust can be very damaging. While it is particularly unsightly in old plants, young hollyhocks can also die from it.
The so-called mallow rust is actually a fungus
How does mallow rust manifest itself in hollyhocks?
A fungus, Puccinia malvearum, is responsible for mallow rust. It causes ugly yellow spots on the upper side of the leaves. On the underside of the leaves, these spots are reddish and raised, like small pustules. Mallow rust often occurs in spring. The fungus can even overwinter in the plant.
This is how you can prevent mallow rust
Prevent mallow rust before you plant your hollyhocks. Choose the location carefully. It should get as much sun as possible and not be too humid. Plant the hollyhocks with a sufficiently large distance to the neighboring plant, it should be about 40 cm.
Proper care also helps prevent it. Water your hollyhocks regularly, especially in summer during the flowering period, even daily if necessary. However, make sure that there is no waterlogging. If the ground is too solid, you can loosen it up a bit and mix in a little sand or gravel. If the soil is poor, fertilize your hollyhocks once or twice a month.
It is also often recommended to cut off the first green leaves in spring, as this is when rust strikes particularly often. A pruning in the fall is also helpful. Although the above-ground green fades in winter, the rust fungus can spread unhindered during the rotting process. You can spray your hollyhocks with horsetail broth or compost.
The most important tips against mallow rust:
- prevent in time
- sunny, not too humid location
- sufficient planting distance
- water regularly
- fertilize in nutrient-poor soil
- remove the first leaves in spring
- Spray with horsetail broth or compost
tips
If you have discovered the first signs of mallow rust on your hollyhock, you should react quickly, the fungal spores are very robust and persistent.