Ailing Schefflera actinophylla (Queensland umbrella tree)???

[infiniteMPG]

We had a small plant growing in the screen covered area of our porch here in west central Florida that we believe is a Queensland umbrella tree (Schefflera actinophylla). It got too large for the porch so we decided to let it spread it's wings and we planed it beside our house a couple years ago. Before long it grew to be the size of a small bus which we didn't mind since it blocked the view of our neighbor's porch. A few weeks ago while walking around I noticed some yellow and empty areas in the recently solid dome of the tree. Checking it out it appears the section facing the north was yellowing a many leaves were gone. This was lush and dark deep green recently and now this is how it appeared :

There were still healthy sections of the tree that looked perfectly healthy :

But where you normally could not even think about seeing the main trunk/branches, these were very visible and void of the thick cover that recently blocked the view :

I was thinking the neighbor's pool pump being nearby may of poisoned it with chemicals but the area nearest the pool pump is actually the healthiest part of the plant.

Just not sure what to do to save this beauty and keep it providing privacy in our yard. Any suggestions or help would be greatly appreciated.

Thanks!

 

[beastmaster]

I always liked Schefflera. I think Florida and here in some parts of Calif. are some of the few places it'll grow well out side. Schefflera needs a lot of light. It could be possible it grown so much its shading parts of its self. That would explain why the north side isn,t doing to well. Maybe a hard prunning might restore its vigor. But it could be a mumber of other things also. too much or not enough water, It could have an imfestation of mits or scale, a freeze or near freeze can cause a lot of dieback. Sorry I couldn't be more specific.

 

[infiniteMPG]

Anything helps. Pruning sounds like a good start and something that will need to be done regardless. We have had a lot of rain lately, to the point of needing a rain gauge that measures in feet rather than inches. The laterals from the septic run in that area, too, but this is still 20 feet from that. Normally stuff grow better near that. I did notice a lot of the stems with missing leaves look lie something chewed the leaves off but I didn't see anything there. Is there some way to see if it's a mite or some other critter eating it? I can post some close up shots of some of the damaged areas.