I want to know if my sunburned cactus(it is part of my landscaping) could be from lack of water as well as the hot summer sun. I live in Phoenix. I've had the cactus for about 13-15 years and last year was the first year that this happened. Maybe it could be an age thing too. Anyway I'm going to get some shade netting I guess and lay it over the cactus and the 3 offspring. I'm sorry I don't know the name of the cactus, but it grows very slowly and has little yellow flowers around the top of it in the spring. Also it has a sort of furry white top. If you can give me any advice about this I would be very grateful to have it. Thank you. Delores
You may have a barrel cactus, and it may have a fungal disease called Pythium rot.
Sunburn is not likely, but wounding and associated fungal infection is a possibility.
Review the following article and see if that makes sense.