After a long time, I noticed this black layer or coating on my plumeria leaves. In this article, I will talk about why these black coatings or spots are formed on the leaves and the treatments.
This black coating is known as sooty mold.
Once you understand how sooty mold forms, you can stop it from appearing on your plumeria leaves.
How does sooty mold or black coating form on Plumeria leaves?
If you are already seeing this on your Plumeria leaves, that means your plant was infested by aphids, mealybugs, whiteflies, or scales.
All these pests are sap-sucking insects, and they leave honeydew on the leaves as discharge. This is the moment when a special type of fungus comes into action.
This fungus is black in color and non-parasitic.
Treatment
Now you already know the reason behind this black coating. If you can stop those pests at the early stage, sooty mold will never be formed like this.
If you are too late and the leaves are coated with this black fungus layer, don't worry, I have something for you.
I will first talk about the manual steps that you should follow:
Fungus loves humid and congested environments. You need to heavily prune the infected leaves. This will help with good air flow.
Now, wipe the rest of the infested leaves and even stems with a damp cloth or a solution of mild dish soap (1 tsp per gallon of water). Once done, rinse with clean water.
Yes, even stems can be infected by sooty mold.
Note: Sooty mold itself is not harmful, as you are thinking. It's just an indication that your plant was previously affected by some type of pest. This can only affect the photosynthesis of your plant by covering the green parts.
With time, the sooty mold will naturally fade as the honeydew source is eliminated.
Neem oil and soap can be tolerated by Plumeria easily. But still, I will recommend testing it on a small area of your plant.
If nothing works, you may try OxiDate 2.0. This might be expensive, but it works well on fungus (like molds).
I am saying it again, focus on eliminating those pests like aphids, mealybugs, whiteflies, and scales.
I have written a dedicated article on Mealybugs treatment - Check it here.
For aphids - aphids on mums.
For other diseases on Plumeria - Plumeria diseases with pictures (From curly leaves to yellow leaves, you will find everything here).
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