Is this a disease or is it normal?

Trouble shoot problems you are having with your cactus.
plantasia
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Is this a disease or is it normal?

Post by plantasia »

Hello everyone,
I am new in this forum.
I am very passionate about plant in general but I have a particular love for tropical plants and cacti.
So I have this beautiful Monvillea spegazzinii f. crestata mostruosa (or at least, I think it is). I noticed that it has this white stuff around that I didn't notice before.
I got worried especially because of these two things:
- my brother gave me as a present a kalanchoe marmorata which soon stated to develop a dusty fungus which I am still trying to fight while it's eating it alive. The kalanchoe was positioned in proximity of the mostruosa so when I saw this fluffy white stuff I immediately connected the two things. In the other plant the fungus was unequivocal. In this one it looks similar but also it could be something else;
- the Monvillea spegazzinii f. crestata mostruosa was a present from my boyfriend's grandmother who already gave us some time ago another plant (a rhipsalis) which was infested with mealybugs. So I was wondering if maybe even this plant came home with those parasites.

Or maybe it's just the plant that has those kind of white stuff as I know some cacti do?
I am really not sure and I am not sure what to do now.
I hope you can give me some enlightenment on this situation. I would really really appreciate it.


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mmcavall
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Re: Is this a disease or is it normal?

Post by mmcavall »

Could it be the new aoreoles of the plant ? In other words, the plant growing
It does not discard the presence of mealybugs but I cant see them in the pictures
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Steve Johnson
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Re: Is this a disease or is it normal?

Post by Steve Johnson »

Those are new spines on the growth point:

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Above-ground mealies are a problem in spring and summer, but you wouldn't see them until then. Root mealies can be a problem in winter, and the following quote from Cactus Nursery in the UK is instructive:

"Root mealybugs (Rhizoecus falcifer) are among the worst pests of cacti and other succulents. They live almost exclusively on roots and the parts of the stem that are below the surface. They are similar to stem and spine mealybugs in that they also secrete whitish, woolly, or powdery wax. Root mealybugs prefer dry substrates. They multiply particularly rapidly during the dry winter dormancy period. Affected plants look pale, become sickly, and gradually die. Plants damaged and weakened by root mealybugs are especially susceptible to fungal diseases."

South American desert species (like your Monvillea) shouldn't get watered at all in the winter if they're being grown outdoors or in a greenhouse -- unfortunately the conditions that root mealies prefer. I don't have any experience growing them as houseplants, although I have a feeling that you could give yours occasional sips if you're keeping it in the house during winter. The plant isn't looking pale or sickly -- winter sips here and there may be enough to keep the root mealies away.

Based on your photos, it appears that you have too much soil in the mix. If that's the case, lean it out by adding pumice, crushed granite poultry grit, or calcined clay cat little for better drainage and aeration of the roots. No need to do it now, but something to think about as your growing season begins in spring.
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FredBW
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Re: Is this a disease or is it normal?

Post by FredBW »

Not saying that is what I think you have. But I have had huge problems with wintertime above ground mealies in the past. I have always been able the see them with a magnifying glass though. I would test a few suspicious spots with a Q tip and rubbing alcohol. The white fuzz mealies make will melt when the alcohol hits them where as areole,or cactus fur will not. I am not sure what rubbing alcohol will do to fungus,but I believe it might wipe off. Don't get too carried away with the alcohol. A little in a few spots wont hurt. But don't give it a bath.
Have you tried wiping it off with something like a Q tip and plain water?
Steves post about root mealies and fungus sounds spot on from looking at your pictures in my armchair thousands of miles away,except as he says. Your plant looks for the most part healthy.
I myself have a plant i suspect might have root mealies that i don't want to repot this time of year. I have some systemic liquid incecticide coming that i am going to try once my soil dries out again. I have no idea what you have available like that in Italy.
Just throwing out some ideas :)
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Steve Johnson
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Re: Is this a disease or is it normal?

Post by Steve Johnson »

FredBW wrote: Wed Jan 11, 2023 3:24 am Not saying that is what I think you have. But I have had huge problems with wintertime above ground mealies in the past.
Were/are your cacti indoors or outdoors during winter? Reason I ask is that stem and spine mealies won't tolerate cold overnight conditions, and since I have my collection outdoors 24/7/365, my overnights are cold enough to prevent above-ground mealies from showing themselves in winter. Could be a different situation for cacti being kept indoors. I agree -- a little alcohol in a few suspicious spots won't hurt.
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FredBW
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Re: Is this a disease or is it normal?

Post by FredBW »

Yea. My problems were indoors. lowest temps maybe got down to the mid to high 40's. But warmer for the most part.
I kind of assumed Italy winters were somewhat like mine. But searching I see they are milder,but still get snow. So I bet the plant in question is living inside right now.
Panu
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Re: Is this a disease or is it normal?

Post by Panu »

Definitely mealybugs, I can see them in every picture.
Panu
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Re: Is this a disease or is it normal?

Post by Panu »

Just quick examples, there are more
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plantasia
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Re: Is this a disease or is it normal?

Post by plantasia »

First of all thank you all for you reply and advice. They are much needed.
I still didn't figured out what happened to this plant.
The difficult thing here is that I was swiftly able to identify mealybugs in other plants but not in this one.
I tried to take more pictures and in some it look it is but in others don't. Also I can't see them with naked eye and I always saw them in that way as they are quite big.
I tried with the Q tip and rubbing alcohol. Sometime it seems to melt other times not. Which I know it's weird and I am baffled because I never had so much trouble in identify a problem like with this plant.
As for your questions about winter time: it's indoors right now. I live near the Alps and I know it might sound counter intuitive since I live in Italy but this is actually a really cold place during the winter. The next week it will be expected a -10°C and usually it stays around 0°C and less for the whole season. So yeah I can't keep the plant outside sadly.
I took other photos with another phone which they might result more clear, I hope so at least.
I will send it to you later as I am at work now.
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mmcavall
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Re: Is this a disease or is it normal?

Post by mmcavall »

Just to help you figure out what is going on, I am sending pictures of my plant of the same species. It is perfectly healthy and nevertheless it has a white stuf. This white stuf is the new growth of the plant. This part of the plant will always be white.
However it seems you have mealybugs also, which are white and may be confusing to you to separate the good from bad.
Hope it helps.
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plantasia
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Re: Is this a disease or is it normal?

Post by plantasia »

Thank you mmcaval for your pics.
The white fluffy stuff on the plants looks a lot like yours.
Here some other pictures as promised:

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plantasia
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Re: Is this a disease or is it normal?

Post by plantasia »

Well I found a good magnifying glass and looked closed to each spot of the plant: it has indeed few mealybugs, tiny tiny and very few. Quite difficult to spot.
FredBW
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Re: Is this a disease or is it normal?

Post by FredBW »

I guess in a way that's good news. It explains the extra white fuzz and you know what you are dealing with. Have you ever used neem oil? I think i would keep attacking the obvious ones with alcohol and a q tip. Then give it a light spray with neem oil in the evening. You want the oil to dry as long as possible before getting light. Might want to leave it in low light a day or two. And then in another week or so give it another spraying for any eggs that might be hatching.
Then in spring repot it,and if you are still seeing them or aren't sure give it a systemic insecticide. That is what i would do anyway :)
Hopefully others will give their opinion,or maybe agree :wink:
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Steve Johnson
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Re: Is this a disease or is it normal?

Post by Steve Johnson »

plantasia wrote: Thu Jan 12, 2023 12:15 am Well I found a good magnifying glass and looked closed to each spot of the plant: it has indeed few mealybugs, tiny tiny and very few. Quite difficult to spot.
Above-ground mealies are good at camouflaging themselves, so you're spot-on about getting a magnifier. Alcohol damages the skin of waxy species, although I don't know if Monvillea has a waxy skin -- be careful about that. My only experience with Neem oil is a bad one, but that was in July 2011 on a single cactus (Stenocactus to be precise), and I didn't know that spraying it in full sunlight would lead to a phototoxic reaction that killed the plant. Such being the case, I don't want to dissuade you from using Neem oil, although it may be better if other members with good Neem oil experience recommend this before you take the chance.

Know your enemy -- this is from the American Orchid Society website:

"Mealybugs have a three-stage life history: egg, larva (nymph or crawler), and adult. Eggs are laid within a waxy coated egg sac produced by the female. The eggs hatch after about a 10 days into the mobile nymphs, the crawlers, that appear as diminutive adults. The crawlers are the most active stage that can move between plants and will develop through several growth periods before becoming adults. Adults of most species are also active. Thus, unlike scales where the crawler finds a suitable site for feeding and remains fixed, mealybugs will move about to find feeding sites."

Plantasia, those tiny tiny mealies you saw are nymphs and/or crawlers, so the few that you have will be easy to knock down before they attach themselves as adults. Unfortunately spraying once won't be enough -- when you kill the first batch, you'll need to do it again when you see more.
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Minnesota
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Re: Is this a disease or is it normal?

Post by Minnesota »

Panu wrote: Wed Jan 11, 2023 12:00 pm Definitely mealybugs, I can see them in every picture.
Having done battle with these critters in the past, and currently from six gifted cacti, I agree with Panu--I feel like I see them in every photo. That doesn't rule out a concurrent infection from a fungus, though; I see the potential for this in addition to mealies. I would treat and isolate the affected plants.

Gloves on, insecticide and fungicide in hand, and keep your chin up. Let us know how you progress.
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