What is causing my Osteospermum Branches to die off, while a few stay green and bloom?

Question

I have an Osteospermum that was here when I bought the house. It was a huge beautiful bush. It produced many blooms after the heavy rains here in CA in 2015/2016. We were still on a drought watering restriction and I watched this large bush with branches reaching out and spreading nicely in the planter area start to go stiff and brown, leaves and branches and just start breaking off at the main stem. I started risking it and watering more, but all of it died except for one branch off the main stem about six inches up from the root ball. It was doing very well and today I noticed, again, a single dead branch with all the leaves stiff and hard and brown. What is wrong with this plant? Whether I water well or water sparingly it continues to go south in the summer months.

Answer 1

Fusarium is a true fungus,
and a common cause of crown rot along with other fungal species and sometimes the condition is linked to bacteria
and nematodes. When a plant is attacked by crown rot, symptoms appear quite quickly with discoloration of leaves
and wilting. The plant eventually dies as the disease effectively separates the plant from its roots