I Would pick all that greenery below the tree to the drip line. Some greens give off a deadly gas.

Jean001a I live in Southeast texas near houston

The grass is not ideal but as it's lived with it so far and it seems pretty old, it's probably not the grass. It would be a good idea to remove it at some point though, it competes with the tree.

It looks to me like the symptoms of some kind of root rot. Has the watering changed in any way in the last year to 6 months? More, less, etc?

Trees that old tend to get very used to how they are watered and a change can cause problems as they are not as adaptable as younger trees. (kinda like people, lol) Root damage can take a long time to get to the point of wilting the plant, so it could be a change that happened a while ago and it's just now starting to show.

It could be one of the many diseases and fungi that can infect roots and the circulatory system of the tree.

Thank you Barb for your input. I will remove the greenery from below and around the tree. Watering hasn't changed. It's right next to our well and it has a slow leak so it has a constant water supply. We've had a significant drought the past few years but this has started within the past year. We've lost half the tree already. Is there anything that can be done to help the tree to become stronger and stop the rotting process? And how do we determine if and which fungus it is?

Are you sure the leak hasn't become larger? That could be it.

It's difficult to determine which pathogen it is, but a broad-spectrum product will treat most of them, so not as important.

The best I know of for soil born fungi would be Agri-fos. Here's the label, it should be available at any good garden center. Or you can buy it direct from Monterey Lawn and Garden co.

http://www.montereylawngarden.com/documents/public/products/Agri-FosSystemicFungicide-2-column-(02).pdf

There is also the possibility it's something else. It's tough to diagnose from a pic. Here's another link to a page of citrus diseases. It's by UC Davis here in CA, so some may not be applicable in Texas, but I could not find a similar page for your state. Hope this helps.

http://www.ipm.ucdavis.edu/PMG/C107/m107bpleaftwigdis.html

You need to investigate the base of the tree to see whether and where it's rotting, and whether those trunks are all satsuma or if some are from the rootstock. It's a bit odd because your main trunk appears to be originating below that old dead stump (which should be cut back). So if that main vertical trunk is carrying satsumas, then the graft point is very low - near or below current ground level. The graft point for citrus trees should always be well above ground level.

I would clear away the greenery, remove some of the dead stump, scrape away some soil to check where the graft is, and remove any rootstock suckers and branches. I think I can see some thin, thorny rootstock growth at the left. If the ground is damp and in contact with the tree above the graft, that would likely lead to rot.

Citrange2 thank you for your input. The stump is from what we cut back that has already died. So we should cut it back more? I see the thorns now thank you. Which is about where the graft point is. It's a few inches above the soil level. We do cover the base with hay during winter and the last year and a half we had some medical emergencies and the hay was left longer than anticipated. Maybe that caused the problems we are seeing?

I'd be curious to know just how long a tree like that can live? Is it possible it's dying because it has run it's course? It's a shame and I hope you find out soon. Is there some sort of agricultural extension office you could bring pics and leave to? It could be anything, but I think someone locally could probably pin point the exact cause.

Our extention agent is new and hasn't been much help