Black spots on Scabiosa leaves. What can I do about this black spot? What causes them? My plants are about three years old in this location. Is this a common problem with older Scabiosa plants?
Black Spots on Scabiosa Leaves.
Certified GKH Gardening Expert
This can become a problem if it is overly wet in your area for a long period of time. This can cause a wide range of infections in the plant. There are many remedies for this using copper sprays, but I use something a little different that works for a very broad range of infections.
Use just a little dolomitic lime, and wettable sulfur around your plant in the soil, and this will help. The sulfur will kill off the infection, while the dolomitic lime will restore the soil pH as it starts to break down. This will be about when the sulfur finishes.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/flowers/pincushion-flower/scabiosa-pincushion-flowers.htm