Black mold on areca palms

[Kalena]

We have black mold on Areca palms planted closely together for a visual barrier. We have sprayed several times with a solution of oil, dish soap and water, but it continues to spread. Is there anybody who has successfully treated black mold out there?

[EightFingers]

You need to use a mix of horticultural oil and liquid copper. I don’t remember the exact ratio, but I bought these at the Garden Exchange and they told me.
It will take at least two sprayings. You also will likely have fire ants in that area.

Puna: Our roosters crow first

[rainyjim]

Do you also see aphids and/or mealybugs (ants will ‘farm’ these insects on plants for their honeydew). These insects secrete a sugary liquid called ‘honeydew’ that a fungi (sooty mold) eats to survive.

You can wash off the mold with soapy water. Using a pesticide like neem oil or horticultural oil to try to ward off the insects may be helpful. The copper, HOTPE mentioned may kill the fungus, but if you wash the fungi off with soap it will probably not return. If you successfully manage to ward off the insects, then the honeydew will not be there for the fungi to eat.

There are more toxic pesticides than copper based pesticides but, relatively, compared to neem and/or horticultural oil it is much more toxic and I would advise caution when using. For that matter I would advise caution when applying any pesticide and make sure to read the label in entirety and do not deviate from the instructions (more is not better).

[Justin]

In my experience, using a systemic (like the Bayer product) that goes into the ground, gets absorbed by the tree roots, and then gets eaten by the bugs, tends to work better than a spray. You shouldn't use a systemic on anything that produces food (e.g., a citrus tree), but it's no issue to use on a palm tree.

[Obie]

We used ant traps under the trees to get rid of the ants and summer oil on the trees to kill the aphids that the ants were farming.

[Kalena]

Thank you for your responses. Does anyone know of someone who treats black mold professionally.?

[dan d]

Power wash


HPP

[bananahead]

its called 'sooty black mold' and is caused by bug poop... usually scale or whiteflies in Hawaii, and often with electric ants (LFAs) present as well, as the ants 'farm' the bugs for sugar (butt dew)
harmless,...
https://patch.com/florida/brandon/sooty-...e-solution
https://www.hunker.com/12178341/how-to-t...sooty-mold
https://www.gardenguides.com/83093-treat...-mold.html

aloha

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save our indigenous and endemic Hawaiian Plants... learn about them, grow them, and plant them on your property, ....instead of all that invasive non-native garbage I see in most yards... aloha