Certified GKH Gardening Expert
This is a very minor fungal infection. They will usually correct themselves, but you can help it along some.
Use DOLOMITIC LIME and WETTABLE SULFUR together in the soil around the tree out about 3 or feet from the trunk. You can also use spray fungicides to treat the top. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
This article will help you with the general care of these trees: https://www.gardeningknowhow.com/ornamental/trees/cassia/growing-cassia-trees.htm
Thank you so much! I will try the homemade mixture and see if it gets better!