I have 35 lime trees about 30 years old, all about 25+ feet tall. They are in pretty good condition but some have sooty green mildew and some have had bark splitting on the trunk and limbs. I spray with citrus soap and it works pretty good to control this. I fertilize one time per year. I have very good drainage. I would like for them to be better. I don't use chemicals. Can you advise?
Lime Trees Sooty Mold and Loose Bark
Certified GKH Gardening Expert
Since sooty mold is often due to pests, I would treat the lime tree with neem oil, as this will not only help with the fungus but will also help with whatever pests are bothering the tree.
Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm