Black Spot on Yucca Houseplant
Thank you for letting me know that my yucca houseplant had a fungus. You told me what to get but I couldn't find it at the store, so I bought insecticidal soap and sprayed leaves in front and back. How would I know if it is working or not? Will the black spots disappear? How would I know and should I spray again?
Certified GKH Gardening Expert
Give it a few days or even a week and the spots should begin to fade away. Generally, most fungal products (like neem oil) will specify how long to treat the plants. It may need another application within 7-14 days.