Pachycereus marginatus (Mexican Fencepost) in trouble!

[sdl]

I received this beautiful Mexican Fencepost in late December. Yesterday, the smaller stem fell over. It looks like it's been rotted out, or otherwise infected. I'm desperate to save the remaining tall stem. It has a few white or tan patches on it.

The nursery told me not to water it. After some research, I noticed people suggested to soak the cactus once a month during the winter. I did that about a week ago.

My friend repotted it using the soil recommended by the nursery. I'm worried it's too tightly packed, and might need more gravel or rocks.

The cactus sits by a south-facing window in my apartment, which is also right next to the radiator.

Should I repot it? Or cut out the white/tan discolorations? Or move it? Or feed it?

Please help!

The rotted out smaller stem.

image1.JPG (69.71 KiB) Viewed 1924 times

The remaining taller stem.

image2.JPG (72.48 KiB) Viewed 1924 times

I took this photo a few days ago and sent it to the nursery, before the smaller one fell over. Obviously, it was already rotting.

unnamed-1.jpg (10.9 KiB) Viewed 1924 times

This is what it looks like today.

IMG_6921.JPG (64.7 KiB) Viewed 1924 times

[iann]

Soil is too rich. You might get away with soaking it every month if you live in Arizona but even then I would suggest that is crazy treatment. You need to stop getting your cactus advice from mumsnet and stick with your friends here

Time to get chopping. Saw through the bottom of the stem with the sharpest knife you can find and keep going until you have a clean unmarked central core. The outside skin might still be marked but that isn't important. Then sterilise the knife and cut another slice off. Put it aside somewhere for the next six months until it has roots.

Then dig up the other stem. Check it still has roots. Check they're alive and attached. Spruce up the soil and replant. It needs as much sun as possible, but sitting by a radiator isn't ideal. They don't mind being hot during the day, but being hot all night as well, especially in winter, is bad.

[cortez753]

Don't think thats a Pachycereus marginatus.

[sdl]

Thank you so much for the helpful responses. What, exactly, should I spruce the soil up with? Is there a middle ground between the five-part formula on this site and commercial cactus mixes (which I shouldn't use, right)?

[KittieKAT]

50:50 cacti and succulent mix (sift out the heavy sticks and stuff) And perlite or try a coarse mix.
Id re cut it till u see healthy tissue using rubbing alcohol to clean the knife with every slice you make, swipe wound with sulfur powder and then let it dry for a few days then pot it up and let it root, be patient and don't water it until u see signs of roots growing or it will rott again.

[Steve Johnson]

KittieKAT has the right general idea, although pumice is way better than perlite. If you live in the US, but you don't have a source already, try here:

http://www.ebay.com/itm/3-5-GAL-HORTICU ... 4ac8424206" onclick="window.open(this.href);return false;

[KittieKAT]

That's usually what i get! But sometimes i opt for the bonsai mix of lava, pumice, turface stone its sometimes smaller grain and looks nice when wet thanks Steve_Johnson very high praise coming from you that u agree with me!