My organ pipe cactus has a problem on one arm See photo. Where is wrong and how do I fix it? Thank you.
Certified GKH Gardening Expert
It looks like it has sustained damage at one time. If this spot doesn't spread, then it will not harm the cactus. If it is spreading, then it could be an infection. If this is the case, then I would recommend applying peroxide to the wound. Also use some wettable sulfur around the base according to the instructions on the package.