Hello, my cactus is getting a light brown discoloration on his arms, I am very worried, please advice on what to do to save my cactus. I stupidly placed the cactus inside a barrel that didnt have proper drainage and when I noticed one of his arms truning light brown i figured it was because of the water, I drilled some holes into the barrel and drained a little water until it was dry. the cactus arms started turning light brown and it seems to be spreading. I am attaching 3 pictures, the first one was taken one week ago, the second one was taken today. Is there any way the cactus can recover from this? What should I do?
Thank you for your time,
The branches can be saved, but since the rot has started from the bottom the whole base of the plant, roots and all, can’t be saved.
First be aware that this is a Euphorbia ammak which has a caustic milky-white latex sap. You need to wear gloves and long sleeves and eye protection when working around this plant. Given its height, this is going to take at least 3 people to safely take cuttings. One to hold the plant, one to hold the branch being cut and a third to do the cutting. If it is taller than it appears you may need a 4th person to help hold the branch as it is being cut. Please make sure you feel safe with all this before you start. I recommend using a serrated bread knife to cut, and blankets to wrap the branch before cutting.
Basically you need to cut each branch off above the rot, making sure there is no rot inside at the cut edge. Spray the cut with hydrogen peroxide and set aside to dry for 2 to 3 weeks.
If you see rot when you cut, keep cutting higher until there is no rot in the branch.
When the branches are fully healed over you can plant them in dry cactus soil and keep dry for a few more weeks. Water only every 3-4 weeks. Do not re-use any of the old soil as it is possibly infected.