Help, my cactus is drying out. Ever since moving my cactus into the hallway, one arm of the cactus is drying out. I live in the UK, so the temperature is not so warm. Usually, the cactus lives in the front room with lots of light. I have since moved it back to its usual position but am worried the cactus is going to die. It's about 2 metres in height with 3 arms. The good thing is one arm has a new shoot! Please help me I've had this cactus 8 years and don't want to loose it! Many thanks Kelly
It could have suffered damage in the move.
Also check the watering. Too much water could cause root rot.
Fungus or disease can also cause the brown or soft spots.
Here is a link with more information.