Q.Cactus is soft and squishy
I am hoping you can help me out with my cactus. Recently, it has become more and more soft/squishy at the top of the cactus and I am having some difficulty determining the cause. 1 theory was overwatering, but I have tried letting the cactus dry out for several weeks and the condition doesn’t seem to be improving. My second theory was some sort of pest like scale. You can see in the attached pictures that there are small white dots all over the cactus, most of them at the bottom but some scattered all over. Do you have any idea what the issue is with my cactus and if it’s possible to save it?
Certified GKH Gardening Expert
It seems that the cactus has been over-watered. This can lead to fungal/bacterial infections. It appears that this is what is going on here. The mottling that you are seeing is a defense response to unfavorable conditions. This is called "scabbing" and is a natural process for the cactus to heal itself.
Although none of this will recover or go away, you can stop it so it does not spread to the new growth. Later on, when it shoots offsets, you can propagate a healthy one. This will rid your cactus of the disease permanently, so long as it receives proper care.
Treatment should be as follows:
There are many fungicides, and many will usually take care of rot in cactus. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
I would, also, recommend treating with a simple mixture. You will need to mix 1/4 peroxide to 3/4 water. Water this in once, and make sure to let the cactus dry very thoroughly between waterings. Most will tolerate very bright light, so you may need to increase air flow, and amount of light that it receives.