Treating sooty mold on palm trees too tall to spray.

[LouN]

Hi,

I live in Southern California. I have King and Queen palm trees which have sooty mold on the lower fronds. They are too tall to spray. Is there a systemic fungicide that can be applied to the roots? I welcome other suggestions too. Many thanks.

[quaman58]

Interesting question. Generally speaking, I have not found that sooty mold is harmful to palms. The last couple years were absolutely awful, and covered virtually everything in the garden, to the degree that I even began to doubt it was sooty mold. For whatever reason, there has been zero problems so far this year, although some of last year’s fronds still show the effects. So, unfortunately, I can’t give you a lot of advice on how to get rid of it. In theory, it’s caused by honeydew being excreted from scale or mealybug at a higher elevation. The idea would be to get rid of the ants,  which gets rid of the mealybug, which gets rid of the sooty mold. But the last couple years just defied explanations, it was on everything. Trash cans, fences, palms. It just didn’t make sense. I have lots of conspiratorial  friends who offer all kinds of explanations, but I’m not sold on any of them yet. 😬

[quaman58]

After re-reading your post, I see that you mentioned that the effect was on the lower fronds. Which to me means that they are almost certainly holdover fronds from last year, when the problem, (whatever it was) was much worse than this year. 

[LouN]

Thank you so much for your replies. The issue really is my neighbor who would love us to remove our palms. as they overhang her yard. The mold has been causing her some issues. I really hope that you are right about last year being a bad year. We have had the lower fronds removed and will be keeping everything crossed that the problem doesn't recur.

I have been busy treating the yard for ants and will keep doing this in the hope it helps.

[John hovancsek]

Use a systemic insecticide. Sooty mold is caused by insects 

[JohnAndSancho]

Make friends with taller people. 

[LouN]

Is there a systemic insecticide that can be applied to the roots? The trees are too tall to spray the fronds.