Question
Brown Spot
I have a brown spot that has formed on my Oreocereus Hendricksianus and is starting to growing in size down toward the base. Cactus in about 20" in height. I live in central North Carolina. I moved the cactus inside about 6 weeks ago. I have a grow light (don't have the model or watt info on hand). I know the plant is wanting to go dormant for the winter so I have cut back on the water and am currently putting them under the grow light every other day for about 6 hours. My indoor temperature is 68 degrees (I know they like a cooler temp during the winter). Any ideas or suggestion on the brown spot and it's cure? Picture attached. Thanks.
AnswerDear Coy,
Is the brown spot soft? I suspect that you ave a bit of rot. Rot usually grows from the roots up but if the plant has had some injury, bacteria or fungus can enter anywhere. It can be either dry or black rot, the latter is more common. If it is spreading, I would say it isn't benign and you need to get rid of it.
How far down on the plant is it? You have a couple of choices. You can cut below the rot to clean tissue or you can try to carve out the rot if the plant is thick enough and the rot isn't too deep. Take a very sharp, sterilized (with alcohol# knife and cut around it till you have clean tissue - no brown, no discoloration at all. Sterilize knife after e each cut. Then take some powdered fungicide #or Rootone if you can find it# and brush the entire area. Let the plant go dormant. No water, no grow light and cooler than 68 degrees. The cut will callous over but you'll have that deformity for the life of the plant.
If the rot is too deep you will have to cut the entire section off. Keep what's below it, in the spring it will develop new growth. For now let it go dormant. Also brush it with a fungicide.
You can the cut the piece you cut off above the rot to where the tissue is clean, let it dry out and callous, and start a new plant. This isn't the best time to root a cactus, but putting the section in a soilless mix of say, half turface or sand and half sphagnum (very slightly moistened) will keep it healthy and it will eventually root.
If you need more help or have anymore questions, please let me know.
Maureen
