Q: My plant has yellow bracts and cream sepals. I noticed today that there is a rust color spot on some of the sepals. Do you know what this is and how to treat it? Thanks,
— Diane, via email
A: Mussaenda is a popular landscape plant for South Florida gardens and landscapes. They are classified in the family Rubiaceae with Ixora, coffee, pentas and firebush. It appears Diane’s Dwarf Mussaenda is the plant horticulturist name Pseudomussaenda flava.
Native to Africa, this shrub grows 4 to 8 feet tall. Best growing conditions include full sun or partial shade with some relief from the hot afternoon sun. Moist soil, but no standing water, and the availability of supplemental irrigation for regular applications of water if the weather presents a long dry spell is good.
Yellow Mussaenda is known as a plant with few pest problems, but the apparent spots on Diane’s plant indicate an issue or two. This plant flowers throughout the year in warm locations.
As flowers mature and prepare to drop from the plant, the petals/sepals can become hosts for various diseases. However, though flower age may be part of the reason spots are occurring, I think other factors are at play.
Flower parts are often colonized by fungal or bacterial pathogens the longer they are wet. This is true for many plants and plant parts,