Hi,
I received this cactus from a friend. It was never looked after so has lots of scale damage.
I've remove a few arms and repotted it with fresh soil.

Still very new to having cactus. I'm wonder if I should be concerned about any of the marks on the new growth? Does it need treating?
Also wondering if the tiny growths are new arms or a fruit?

Is there anything else I should to for it's health or just leave it as it is now?

I'm in Australia and it's under our patio with some morning sun, then late arvo sun.

Thanks for your help.

Are the scarred parts of the stem due to cochineal scale (aka scale insects)? I am having a hard time resolving the exact cause of that stuff.

The insects are pretty easy to identify if you catch them in the act. They should be hunkered down against the skin, fairly firmly attached, but you can dislodge them easily with a sideways motion (using a toothpick or toothbrush or your tool of choice). The scar that remains is the exact size of the insect's body, including the hard waxy outer layer.

The adult scale insects lose their ability to walk once they are hunkered down, so removing them from their vampiric embrace means the end for them. However their progeny (probably invisible to the naked eye unless you're an advanced insect hunter) remain mobile, at least until they find a spot they like. So curing scale usually requires removing the adults and then spraying the plant down with 70% ethanol or insecticidal soap to ward off the youngsters.

The damage in the pics does not look like the scale damage I've seen, but that doesn't mean it isn't just some incredibly advanced infestation (now resolved, but having left scars). The important thing if you're pretty sure it was scale insects is to watch for the adults, which are immobile and easy to spot. If you don't see any bugs stuck to the plant, you can reasonably presume what you're seeing is simply their aftermath, and something the plant will grow out of.

I don't honestly know what else could be going on, maybe some fungal disease, but it's not anything I recognize. Try to be observant and see if the scarring is progressive. If it isn't, I'd leave it and concentrate on good care (making periodic stops to look for insects). This is what you would be looking for (camouflaged in the picture, near the base of the leaf):



The tiny growths are fruits. They turn purple when they are ripe. They are edible, like a berry, but only when really ripe.

The plant should be able to take lots of sun, pretty much all you can throw at it, provided temps aren't in the red zone. Morning sun should be great. Look for compact new growth to confirm you're providing enough light. Water well, to completion, and then wait for the soil to go dry most or all of the way at depth before watering again (not just at the surface, which dries out much sooner).

You do have the option of starting a new plant from a cutting, if you want to have something that's all green down the road. Maybe that would be good to consider once you're more comfortable you've got the care mastered, and we can provide step by step instructions.

Thank you for that. I've had a good look over and don't think there are any of those small bugs you mentioned.
I've posted a picture of the 'freshest looking marks.its like the start off as yellowing under the skin then turn scaly/woody.
I just assumed it was scale.
The cactus had been neglected by the previous owner.

I have 3 cuttings that I removed when I repotted it as the shape was a bit awkward.
I've put cinnamon on the cuts.
The new growths on one of the cuttings is showing the same marks.

It may be very counter intuitive, because I have read that you live in a relatively dry and hot part of Australia, but to me a lot of those spots look like they are fungal in origin. I wonder if treating the plant and the soil with a fungicide on a regular basis would help keep the new growth clear. The old growth is never going to recover.

Alternatively it is the corking disease, which means that the plant develops 'bark' much quicker than it normally would, in some cases eventually overtaking any new growth... not sure if there is an obvious treatment for that.

Still I think a regular all over fungicide treatment would not hurt and it might help.

Thank you. Which fungicide do you recommend?

We do get some very wet cold winters here and I have had fungus in my cactus before ( but a black fungus, not similar to this)

It is hard to say if what is available here is easily available in Australia, but some common ones are Liquid Copper of liquicop fungicide. You want to be careful using that as it can leave pretty severe blue staining that can turn into chemical burn marks. So I tend to treat at night and out of direct sun, followed by a rinse a day or so later.
Another common one is Daconil.

But there any many out there. The problem with fungal infections is that the source may not always be obvious as spores can easily disperse (and thus arrive) by wind and of course the best way to eliminate the issue is to eliminate the source, but it may not always be in your control to do that, so it may be a treatment you have to keep doing every so often.

This looks like similar damage to what I've seen on some Epiphyllums occasionally, and Schlumbergera. Some tiny critter gets under the surface and eats away just under the surface eventually creating a separation of that section from the main part of the plant if not removed. Whatever it is, it's too small for me to see more clearly than that there are tiny black dots at the edge of the damaged area. I remove affected areas when I see this and it doesn't seem to continue after that. The first few times I saw this kind of damage, I thought it was a rodent or other larger critter taking significant bites from the edges, but then I noticed the black dots, and how the edges of the damage were "sealed", for lack of a better word, and before I started removing the damaged areas, noticed that they were slowly getting bigger but not in a way that would have come from a larger animal taking actual bites.

I totally agree with Purpleinopp. We have had issues with the Epiphyllums for years until we started
spraying with half and half rubbing alcohol and water twice a season. Knock on wood the tiny critters
are staying away.

Did you ever figure out what they are? I'm surprised the alcohol works because they seem to be inside the plant, from what my sight-challenged eyes can see.

I haven't had that problem on epiphyllums, possibly leaf miners?

karmahappytoes said:I totally agree with Purpleinopp. We have had issues with the Epiphyllums for years until we started
spraying with half and half rubbing alcohol and water twice a season. Knock on wood the tiny critters
are staying away.

Hm... Will try this half alcohol method, as I have some cacti have those and so far I can not do anything about it

purpleinopp, they arrived here when I traded with some folks in OR. They stated that they have this all over their eppies and I set the plants aside but somehow several around it got it. The next year most of ours had it. No one here could tell me what it was or how to handle it. So I just started playing with assorted products and the rubbing alcohol I use to clean the clivia's water stains and it worked.

Thank you! If I see that again, I'll definitely try that.

purpleinopp said:This looks like similar damage to what I've seen on some Epiphyllums occasionally, and Schlumbergera. Some tiny critter gets under the surface and eats away just under the surface eventually creating a separation of that section from the main part of the plant if not removed. Whatever it is, it's too small for me to see more clearly than that there are tiny black dots at the edge of the damaged area. I remove affected areas when I see this and it doesn't seem to continue after that. The first few times I saw this kind of damage, I thought it was a rodent or other larger critter taking significant bites from the edges, but then I noticed the black dots, and how the edges of the damage were "sealed", for lack of a better word, and before I started removing the damaged areas, noticed that they were slowly getting bigger but not in a way that would have come from a larger animal taking actual bites.

Do you have a pic of the damage , would be interested to see what it looks like
Steve

@Steve, maybe this? I have 3 cactus that have those, will start the alcohol spray tonight..

Kaktus said:@Steve, maybe this? I have 3 cactus that have those, will start the alcohol spray tonight..

Dont think this is scale. Last one is definitely some critter but not scale. Scale is...smaller. Monocot plants catch it too-aloe, agave, hippeastrum etc...
it looks like a white/gray oval with a yellowish core.
This looks like mite damage I think. That or something else...

ketsui73 said:

Do you have a pic of the damage , would be interested to see what it looks like
Steve

No, but if I see it again, I'll try to get one.

While watering a few mins ago, I saw this on the back of a leaf. I had cut all of this off before I brought the plant inside. IDK what this is but I'm 100% sure it's not mechanical. This plant hasn't been moved for months.

From that last picture I would almost say that looks like caterpillar munching damage - the black specs could be poop, unless those specs are tiny critters. I had not ever seen caterpillar damage on a cactus until this late summer/early fall when I found a few caterpillars munching away at the tip of a cactus in my back yard.

The damage in the other two images could be a worse case of the same or something else.

I wouldn't rule out a caterpillar but I'm not seeing any or any droppings on the table below. When it got too cold, I just picked plants up & brought 'em in, so a lot of critters could have possibly been brought in. This particular pattern of damage (knock wood) seems to be confined to Epiphyllum & a few other epiphytic cacti, like Lespismium and Hylocereus.