Cactus sick with some white/beige spots/patches

[Lordexeros]

Hello,

I have recently noticed that my cactus is having some white/beige spots/patches on his whole body. It is something normal or is it an infection? What can I do?
It survived quite well considering that I have saved it from a supermarket 2 years ago. It was half rotten, which is why he has some cuts. The new leaves (6 months old) are quite healthy (some of them have some light white/beige spots on the basis). One of the old leave (the one on the left with a cut) looks very dry and will most probably fall soon. Can I take it away and maybe put in the soil to reproduce it or should I just wait until it falls and throw it away?

Thanks a lot for your help.

Best,
David

[FredBW]

You might have scale. We really need a close up of the spots to really tell.
Here is a video that might help you decide if that is what it is.
https://www.youtube.com/watch?v=JqTq4yB1ayI
If you do put alcohol on it,after a day or 2 for it to recover I would get it outside in the sun and wind.
Cacti can survive inside. But in order for them to thrive they need to be outside. They soak up sunshine.

[Steve Johnson]

I have recently noticed that my cactus is having some white/beige spots/patches on his whole body. It is something normal or is it an infection? What can I do?
It survived quite well considering that I have saved it from a supermarket 2 years ago. It was half rotten, which is why he has some cuts. The new leaves (6 months old) are quite healthy (some of them have some light white/beige spots on the basis). One of the old leave (the one on the left with a cut) looks very dry and will most probably fall soon. Can I take it away and maybe put in the soil to reproduce it or should I just wait until it falls and throw it away?

First, see this:

viewtopic.php?t=43819

There are a couple of reasons for knowing about your geographical location:

• Your local climate -- if we know what it is, this will factor into what we can recommend.

• The products which are available to you -- potting media and pesticides. This also factors into what we can recommend.

I agree with Fred -- we'll need a close-up of the affected areas. Here's something that may help you identify the problem:

https://www.cactiguide.com/cactipests/#bugs

If you do have a scale problem, alcohol is only a short-term solution. The long-term solution is a systemic insecticide called Imidacloprid, although I don't know if you can get it. If you live in the US, you can. If you live in another country, it depends on the country.

[Lordexeros]

Dear Fred and Steve,

Thanks a lot for your kind help.

I have put my city on my profile (I live in the North of Germany, which means that the summer is quite nice = 20-30 degree celsius, with at lot of sun light (sunrise 5 am and sunset 9.5pm). But in Winter it's cold (-5 to 10 degree celsius I would say), with not a lot of sunlight and a lot of rain.
It's true that I could put my cactus outside in sommer, but what about rain? It can rain quite a lot (4-8 days per month). Now, the cactus is inside the whole year. It has light from around 6 am to 1 pm. On the other side of my home I have other cactus which are in better shape because they get sun the other part of the day, which is way warmer.

It can be a scale, but I am not sure, I have attached few more close-up pictures.
On the first picture you can see that It gets out with my nails without damaging the cactus. And the light spots, even just while rubbing with my fingers.

Thanks

David

[Steve Johnson]

Hi David,

Your location info is quite helpful, so let's see what we can do...

I don't believe you have a scale problem, so if that's the case, the crusts are being caused by another problem. There are only 2 possibilities I can think of:

• Calcium carbonate left behind from watering with hard tap water. Understandable if it's around the base of the plant, although I don't know how it would get that far up on the pads you cut. By the way, what's the dark brown stuff you put on the cuts? It looks like some sort of epoxy-type material.

• For good or ill, everythings starts out in the roots. It appears that you're growing the Opuntia in potting soil -- too heavy and rich in organic materials for growing desert cacti. I highly recommend that you lean out the soil by mixing it with mineral gravel. IMO horticultural pumice is best, although I don't think you can find it. From Amazon Germany, try this instead:
  
  https://www.amazon.de/HanseGrand-Expand ... 9hdGY&th=1
  
  My default recommendation is a mix of 50% soil and 50% mineral gravel. This will improve drainage with better aeration for cactus roots to grow in. Better root growth = healthier stem growth, and that may solve the crust problem.

Question about the rest of your cacti -- do you keep them indoors or outdoors during the spring-summer growing season?

[jerrytheplater]

Just in case it is not obvious David, When Steve says to lean out your potting mix with gravel, he means you will have to completely repot your plant. I am just concerned you may think you can mix it in while the plant is still in the pot.

If I'm way off base, just chalk it up to me being overly cautious.

[Steve Johnson]

Just in case it is not obvious David, When Steve says to lean out your potting mix with gravel, he means you will have to completely repot your plant. I am just concerned you may think you can mix it in while the plant is still in the pot.

If I'm way off base, just chalk it up to me being overly cautious.

Good call, Jerry, and IMO there's nothing wrong with being overly cautious. One important thing I should mention...

Whenever you unpot cacti, you'll need to clean the old soil out of the roots as thoroughly as possible. When they're dry after cleaning, repot in fresh, dry mix and let them settle in for 2 weeks before watering. David -- if you lose some roots in the cleaning process, don't worry. Your Opuntia will grow new roots.

[Lordexeros]

Hi Steve and Jerry,

Thanks a lot for your valuable information. I learned a lot from your tips. Looks like growing cactus is not that easy and requires a bit more than just loving cactus and plants
Sorry for my late reply, I was on holiday for few days. Nevertheless, the cactus still looks the same and I will take care of it with your advices.

It could come from hard tap water indeed. Should I give my cactus something else than tap water (the water is medium-hard here I would say)? And sometime I give them some "cactus special fertiliser" and this may be too much. And 1 time per week watering is maybe too much as well.

What I used as a soil is simply a pre-mixed soil for cactus I bough in a shop. What do you mean with 50% soil? Can it be whichever type of soil or should it be something specific for cactus?

And for summer I keep them inside because we still have a lot of rain outside (4-8 rainy days per month I would say) and there is not a lot of sunny place on the small balcony, unfortunately.

I closes the cuts with this (https://www.raiffeisenmarkt.de/neudorff ... VDEALw_wcB), from a German shop. It is basically a mixture of latex and minerals to help close the wounds (mainly used when you prune apples/fruits trees).

Thanks a lot again for your kind help

[Steve Johnson]

We have a few things to unpack, so let's get started...

It could come from hard tap water indeed. Should I give my cactus something else than tap water (the water is medium-hard here I would say)? And sometime I give them some "cactus special fertiliser" and this may be too much. And 1 time per week watering is maybe too much as well.

If you have only 1 cactus, water it with distilled water you can get at your grocery store. If you're able to store rainwater, that's even better. Do you have a rain barrel or can you get one? Assuming that your domicile's roof has rain gutters (they generally do), "downspout" into the rain barrel captures the rain. And you can use stored rainwater to water all of your plants. I'd like to evaluate your fertilizer and see if it's well-suited to cacti. Please post a photo of the fert's label which shows its chemical analysis. My basic "rule of thumb" for identifying good cactus and succulent ferts:

• Phosphorus (P) lower than nitrogen (N), potassium (K) higher than both.

Once I see the breakdown of all nutrients on the label and determine the NPK ratio, I'll let you know if your fert is good for cacti. If it's not, I'll try to find better options for you.

What I used as a soil is simply a pre-mixed soil for cactus I bough in a shop. What do you mean with 50% soil? Can it be whichever type of soil or should it be something specific for cactus?

Your pre-mixed cactus soil may actually be fine, but pre-mixes tend to be too heavy on soil and too light on mineral gravel for optimal drainage and aeration of the roots. If you mix your cactus soil with mineral as I recommended, the 50/50 soil+mineral mix should work well. Be sure that you mix the ingredients thoroughly, don't layer them as some new growers try to do. Water from the top and make sure that you see drops of water coming down out of the drain hole. Water every 2 weeks in spring and summer, don't water at all in fall and winter. When you fertilize, any nutrients not taken up by the roots stay in the soil after it dries out, and those nutrients are released back to the roots in subsequent waterings. My best recommendation here -- fertilize with every 3rd or 4th watering.

And for summer I keep them inside because we still have a lot of rain outside (4-8 rainy days per month I would say) and there is not a lot of sunny place on the small balcony, unfortunately.

Lighting technology has come a long way since the "olden times" when the only indoor lights we had were fluorescent and incandescent -- not good for growing plants of any kind. LED is a genuine game-changer, so check out the selection of grow lights on Amazon Germany:

https://www.amazon.de/s?k=grow+lights+f ... nb_sb_noss

With a good grow light setup, your Opuntia may not have to be the only cactus you can grow indoors. (Am I giving you ideas? )

I closes the cuts with this (https://www.raiffeisenmarkt.de/neudorff ... VDEALw_wcB), from a German shop. It is basically a mixture of latex and minerals to help close the wounds (mainly used when you prune apples/fruits trees).

Sorry, but I wouldn't use it on cacti. Take a sharp knife and sterilize it with alcohol, then cut right below where you applied the Malusan product. Give the exposed tissue a liberal dusting of sulfur powder (also available on Amazon Germany). Sulfur is a highly effective fungicide, so that's all you need. Unfortunately the Malusan prevented your Opuntia from growing new pads on the cuts. Expose the tissues again, apply the sulfur powder, let the cuts dry and form a callus -- then you should see new pads starting to grow. Probably too late for it this year, but look for it next spring.

Thanks a lot again for your kind help

You're welcome!

[Tom in Tucson]

Just to knit-pick a little: I think your Opuntia is a Consolea rubescens (Road Kill Cactus).

[Minnesota]

A very interesting cactus for you to save. LLIFL has some interesting pictures and cultivation notes, particularly for watering, hardiness, and frequent mentions of the potential for rot from overwatering or exposure to cold; one description is very similar to the pictures you posted.

Best wishes with the care and resolution of these spots.

[Lordexeros]

If you have only 1 cactus, water it with distilled water you can get at your grocery store. If you're able to store rainwater, that's even better. Do you have a rain barrel or can you get one?

Yes, I have a small rain barrel and this could give me enough water for my cactus. I do have more than 1 cactus, much more around 15 pots with one or more cactus/succulents. But I can buy some distilled water as well. It's not too expensive.
Most of them look pretty well, but some of them are not that well.

I'd like to evaluate your fertilizer and see if it's well-suited to cacti. Please post a photo of the fert's label which shows its chemical analysis.

I am using this one: https://www.amazon.de/Kakteendünger-dic ... 63806&th=1

I am unfortunately not at home for the label (can send it later), but from the internet I found that it has NPK 5-5-7.
But the last time I gave some fertiliser was almost 3 months ago.

Your pre-mixed cactus soil may actually be fine, but pre-mixes tend to be too heavy on soil and too light on mineral gravel for optimal drainage and aeration of the roots. If you mix your cactus soil with mineral as I recommended, the 50/50 soil+mineral mix should work well. Be sure that you mix the ingredients thoroughly, don't layer them as some new growers try to do. Water from the top and make sure that you see drops of water coming down out of the drain hole. Water every 2 weeks in spring and summer, don't water at all in fall and winter. When you fertilize, any nutrients not taken up by the roots stay in the soil after it dries out, and those nutrients are released back to the roots in subsequent waterings. My best recommendation here -- fertilize with every 3rd or 4th watering.

Amazing! Thanks a lot for the tips. True that the pre-mix I use don't have that much mineral gravel. Will make the necessary
And related to watering, every week is definitely too often. Will do as you suggest.

Lighting technology has come a long way since the "olden times" when the only indoor lights we had were fluorescent and incandescent -- not good for growing plants of any kind. LED is a genuine game-changer, so check out the selection of grow lights on Amazon Germany:

Sounds great Will definitely look for few small lamps, maybe I can put some cactus under it alternatively for few hours. It would be too much (especially in term of place) to have lights for each of them.

Sorry, but I wouldn't use it on cacti. Take a sharp knife and sterilize it with alcohol, then cut right below where you applied the Malusan product. Give the exposed tissue a liberal dusting of sulfur powder (also available on Amazon Germany). Sulfur is a highly effective fungicide, so that's all you need. Unfortunately the Malusan prevented your Opuntia from growing new pads on the cuts. Expose the tissues again, apply the sulfur powder, let the cuts dry and form a callus -- then you should see new pads starting to grow. Probably too late for it this year, but look for it next spring.

Nice, I will try next year

Thanks again for all the nice tips and kind help. Really learning a lot from you. I have few more cactus that may need some help. But I am sure that with the use of rain/distilled water and that having better soil and fertiliser will already help a lot.

Just to knit-pick a little: I think your Opuntia is a Consolea rubescens (Road Kill Cactus).

Thanks, it's good to know

A very interesting cactus for you to save. LLIFL has some interesting pictures and cultivation notes, particularly for watering, hardiness, and frequent mentions of the potential for rot from overwatering or exposure to cold; one description is very similar to the pictures you posted.

Thanks a lot. What is LLIFL? I tried to Google it, but I found nothing. Can you please share the link with me?

[Steve Johnson]

A very interesting cactus for you to save. LLIFL has some interesting pictures and cultivation notes, particularly for watering, hardiness, and frequent mentions of the potential for rot from overwatering or exposure to cold; one description is very similar to the pictures you posted.

Thanks a lot. What is LLIFL? I tried to Google it, but I found nothing. Can you please share the link with me?

That's Llifle:

http://www.llifle.com/Encyclopedia/CACTI/

Good resource, but not the best place for getting cultivation advice. By the way, I'll look into your cactus fertilizer later this weekend.

Thanks again for all the nice tips and kind help. Really learning a lot from you. I have few more cactus that may need some help. But I am sure that with the use of rain/distilled water and that having better soil and fertiliser will already help a lot.

My pleasure!