Does anyone know what is happening to my cactus. It was a beautiful specimen when I got it and was fine for a year or so, but then it gradually started with the browning and weird skin disease. It has been getting progressively worse and quicker to attack. It aslo seems to disfigure new grownth and existing growth. Did start near bottom I think, but seems to attack quite quickly on new growth as well. It's been in this spot for several years. I tried neem oil last year, but didn't seem to work at all. It continues to attack when I move a limb to a pot so I think it is systemic (?).
It is not as green as it was when I first planted or as green as the limb from it that I planted in a pot (see picture) It is winter here in California. Perhaps it doesn't like as much sun as it's getting.