persistent yellow of all leaves on jackfruit & acerola

[rtdrury]

I'm seeing persistent yellow of all leaves on one of two young jackfruit plants, and same thing with acerola plants.  The one jackfruit and the one acerola with the yellow leaves may have roots of large oak trees strangling their roots.  When the soil dries around their trunks, it is very hard, and I'm mostly sure this is due to a very dense root mass surrounding the trunk.  I cut the soil vertically down one foot with a saw in a diameter of 1.5 feet around the trees to sever the trunks of this possible oak root mass, and two weeks later I don't see any changes in the plants with yellow leaves.  Other plants have had root rot in this area of the yard but the root rot symptoms are immediate death, not persistently yellow leaves.  Has anyone seen this symptom? 

[850FL]

Is the old growth yellowing or new growth? Also is the yellowing of each leaf progressing from the bottom of the leaf (near the petiole) towards the top, the top to bottom, or sporadically?

Most issues I have with yellowing are either
1) underwatering (accompanied by wilting)
2) underfertilizing (which sometimes can be caused by overwatering and leaching nutrients)
3)overfertilizing (which seems to cause some leaves to burn or rapidly turn yellow and then progress to crusty brown)
4) improper pH (often due to overfertilizing or fertilizing with a non-pH-balanced fertilizer.. can show up in various ways, as some nutrients get blocked out, usually accompanied with some sort of yellowing, burning, or chlorosis of the leaves..
5) #3 and 4 can also cause root damage and thus cause yellowing leaves. AND SO WILL MOLES!!! Actually most of my saplings are affected sooner or later by these uglies (also exasperates #1). They will cause stunted growth and yellowing leaves/leaf drop for SURE.

It's also possible that you're right about the oak root strangulation. How long have these plants been established? I would have gone further out with the saw.. if anything start cutting oak roots around the base of the oak as opposed to the base of your plants.. you may have cut some of their feeder roots in the process..

Also make sure the soil doesn't dry out too much..

[rtdrury]

Thanks for your thorough reply.  So it's all leaves, whole leaf, that is yellow on both acerola #2 and jackfruit #2, while each has a healthy green companion, same species/size/age nearby, without the dense oak roots.  So I really don't think the watering/fertilizer amount are at issue.  Turns out the jackfruit finally died and the root crown was girdled from soil line down 1.5 inches, that is, the outer cambium layer was gone. Below that, the root was healthy looking.  It doesn't look like the same kind of root rot I've seen on other trees because that is black, and extends into the feeder roots.  I don't think this was a mole because the familiar tunnel indicators are nowhere in sight.  I dug down on the acerola to look for same symptoms under soil line, and that root crown looks healthy.