My Beautybush seems to have a rust discolouration on the leaves, especially the ones that produced flowers, should I prune them off or cut back the whole bush? I am reluctant to spray with anything.
Lucky you to have a Chinese beauty bush (Kolkwitzia amabilis) – it is gorgeous! And take heart – it is not generally affected by insects or diseases.
If the rust discolouration seems to be on the leaf tips only, this could be due to lack of water.
As well, during the heat of the summer, the plant leaves can be attacked by rust, which appear as spots on the leaves. I did not find any specific type of rust that affects the beauty bush, so consulted general references relating to leaf rust diseases.
Rust is usually caused by a fungus, and is unsightly but typically does not kill the plant, although it can weaken it. Good cultural practices that should be effective in getting rid of the rust include:
- Clear plant debris from around the base of the plant (don’t compost this material – discard in garbage, as rust spores can survive composting)
- Make sure the soil around the plant has good drainage
- Pick off affected leaves (if there aren’t many of these) – if you removed huge numbers of leaves, this would affect the plant’s health
- Water carefully to avoid getting the leaves wet (and water early in the day so the plant can dry off during the day)
- Prune the plant to ensure good air circulation and light penetration among the leaves. You don’t need to cut back the entire bush. Here’s a link to an earlier Q&A that discusses pruning the Beauty Bush
- Prune back any other plants that might be too close to your beauty bush (don’t overcrowd plants)
- Mulch helps to reduce stress to the plant – a 3-4 inch deep layer around the bush (with a minimum 2 inch space between the mulch and stem area to permit air circulation)
- At the end of the growing season, remove all diseased leaves/plant material in case the rust spores survive our winters (again, do not compost this material)
- When fall comes, add compost to the soil around the plant to provide nutrients for the coming months.
You may want to speak with someone at your local nursery soon (take a cutting of some affected leaves, in a sealed clear plastic bag), for a definite diagnosis of what is affecting the beauty bush. If it is rust, for example, and the above strategies do not work, the nursery expert may recommend products that will be effective and would advise when to apply them (timing is important).