SICK T. Peruvianus - Purple areas and sunk in flesh. WHY ???

[jheaton]

Hello, I just noticed this when I when to water these today. 1 cactus is severely messed up at the top with purple areas and sunk in here and there. It's been about 2 weeks since watered. I have several but only a couple are like this. Hopefully it stays that way. I'm sure I'm going to have to cut the top off, I just really want to know Why is this happening to try and prevent it in the future. Thanks in advance for any help or suggestions. These are Trichocereus Peruvianus grown from seed.

[Andrzej1972]

Certainly some feat. Don't wait and don't even try to treat the symptoms. Cut off the sick part and cover the wound with some protective agent.

[Steve Johnson]

Hello, I just noticed this when I when to water these today. 1 cactus is severely messed up at the top with purple areas and sunk in here and there. It's been about 2 weeks since watered. I have several but only a couple are like this. Hopefully it stays that way. I'm sure I'm going to have to cut the top off, I just really want to know Why is this happening to try and prevent it in the future. Thanks in advance for any help or suggestions. These are Trichocereus Peruvianus grow from seed.

You have a fungal infection. Good news is that it's in the upper part of the stem. Bad news is that'll go down the meristem, so I agree with Andrzej1972 -- cut ASAP before the situation gets worse. Here's what to do:

• Sterilize a sharp knife with alcohol.

• Cut below the infected part. If you see nothing but healthy green tissue, you're safe. But if you see even a tiny spot of discoloration, cut more until you don't see any at all.

• If you need to cut more than once, sterilize the knife with each cut.

• Make sure to cut at an angle so that water won't pool up on the top of the cut.

• Give the exposed surface a liberal dusting of sulfur powder to prevent fungus or mildew from being a problem as the cut forms a callus. Don't even think about watering the plant until the new growing season begins next spring.

Your T. peruvianus are well beyond the seedling stage -- they should be dormant now, so I'm not sure if watering them is a good idea in the fall and winter. Watering when they didn't need it after the end of summer could explain why you got the fungal infection.

[jheaton]

Thanks for your reply guy's, I really appreciate it!! Is there a concrete reason why this happens?

[anttisepp]

Cold, humidity, low light...

[Steve Johnson]

Cold, humidity, low light...

Exactly -- a good argument in favor of not watering T. peruvianus during fall and winter once seedlings safely pass the "tender" stage and become juvenile cacti. IMO this rule should apply to all species of desert cactus, not just peruvianus.