Is my Mexican Fence Post dieing

I had the backyard of my new house landscaped in February of 2013, but we did not move into it until the past July. When we got here most of the landscaped looked good and survived, but just in the last couple of weeks I noticed that the smallest part of the Mexican Fence Post is looking poorly. (see pictures)
The yard is on a drip that runs daily for 30 minutes. I am concerned that it is rotting but It is not soft. Does anyone know if it is dieing? Is it the whole plant or just the small part? How should I handle this?
We moved here from Wisconsin so I am a novice with desert plants.
Thanks for any help.
Dee

I think your watering schedule is not the best for cactus. I believe your cactus may be rotting from too much water. Cactus usually don't need that much water. Once a week seems more than enough for good growth. They will get along with almost no water once established.

I say cut away the smallest column ASAP. Check to see if there is any rot at the base, and if not, just let it callous...then pray.

I've seen Mexican Fence Posts recover nicely when only one column goes bad.

I agree with Judyb and Minime, especially since this year's monsoon was so wet compared to 2013 and to me at least it seems it got colder at night sooner this year compared to last year when we did not really have much of winter at all. So the watering regime might not have been so bad as to cause any problems before. However, this year could easily be a different story.
I have not watered my yard since September, plants in pots I did water because pots dry out so quickly, but I know the soil in my garden is still pretty moist not that far from the surface since I have been digging holes to plant a lot of new plants in space opened up by the flowering of some Agaves.
How to handle the plant: for now turn the drip off if you can - but if it is also feeding something that needs water then find the emitter near the plant and remove it. Dig around the plant and try and determine how far reaching the decay is - if just associated with the small off shoot cut that away as close to where the shoot connects to the main plant and let everything dry out before covering the cut, if it is affecting the rest of the plant you will likely see it start developing the same symptoms as the small offshoot. Hopefully stopping watering and letting it thoroughly dry out will allow it too recover - cacti are remarkably resilient, but if one thing will get them it is too much water combined with cold temperatures at night.
If it looks like most of the roots are affected (see how solid the two major trunks of the plant are rooted - while possibly a little bendy the plant should not be very easy to move in the ground if the root system is mostly healthy) you should uproot it and cut most of the rot away and leave it to dry out. The rest of the plant can then probably be saved as it can reroot from cuttings, that is actually how I got one of my Mexican Fencepost cacti - a large cutting from a friend's plant.

This message was edited Nov 19, 2014 11:07 PM

This message was edited Nov 19, 2014 11:08 PM

Good advice!

I agree that your watering schedule needs some adjusting! Cactus plants generally need to dry out completely between watering, then have a good deep soaking. How often depends on your soil, natural rain and temperature--more when it's hot and dry, way less when it's cool and dry, none when it's been raining. If your soil is mostly clay, it takes a long time to dry but then does well with an infrequent long slow soak that encourages the roots to spread and also go deep. I think the little new shoot is probably done for, but the main part of the plant might survive and carry on if given a chance to dry out and recover. Good luck with it!

Thank you all! Talked to my neighbors gardener and he is going to change my drip to ones I can turn off and on so plants that need it will get water and I can control the ones that need less.
Guess I will try removing the small arm and keep my fingers crossed.

It also looks to me like it might be buried too deeply- anybody else think that?

It looks pretty deep to me too, EileenAZ. I would pull stones away from the plants so you can see what is going on better ... and definitely lessen the amount of water!