Cylindropuntia bigelovii

[M.B]

I am unsure if I am looking at an issue that needs attention or if I am looking at normal California high desert weathering. First pic is the top of the cactus. First I thought scale, but it does not pic off like scale. I’m leaning toward natural weathering/desert debris. Without having seen this before I wanted to get more eyes on. The same buildup appears on all of the glochids (more on the upper glochids (larger) than lower (smaller). They look like tiny barnacles LOL. Thoughts?

[M.B]

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[kak tus]

Looks nasty.. I'm going to wager it's some sort of fungus. Perhaps this post might offer some insights:
viewtopic.php?t=14438

[hegar]

Well, the images you posted are kind of interesting to say the least. While a whitish substance can be formed because of calcium in the irrigation water that has evaporated, pesticide residue, or perhaps dried up plant sap or other exudates, the presence of these barnacle-shaped bodies makes this diagnosis impossible. As far as fungi are concerned, I have not ever seen anything resembling this on a cactus. For fungal fruit bodies, e.g. aecial cups, pycnidia, perithecia, etc. they are too large, for galls - be they of animal or plant pathogen origin - they look too small.
My guess is, that you are dealing with a problem caused by some kind of animal, perhaps something related to scale insects in the insect order Homoptera, which includes the scale insects. The barnacle-shaped bodies may even be insect eggs, but I cannot tell enough by looking at the pictures to come to that conclusion.
I did copy your images and will show them on Monday to my entomology colleague. Perhaps he has an idea of what this might be.
Your photos are of good quality, but they may still not be magnified enough to show enough detail. If I had the specimen, I could photograph one of these globular bodies, showing minute structural features and of course use the microscopes to examine whatever it is.
If you do have a decent hand lens with a magnification level of 10x perhaps, you could carefully remove some of this material with a brush or a probe and examine it carefully.

Harald

[M.B]

kac tus and Harold thanks for the info. Harald I have looked at this stuff under a loop, but I really have no idea what I am looking at. If I noticed something moving I may have had a chance, but none of this is currently moving at a rate the eye can detect. I do have more than one and I am willing to send you one with no need to return. With your resources a better shot at identifying this could help others along the way. PM an address and I will ship.

[7george]

Tips of some newly growing spines? Areoles often increase number of spines with time. Monitoring those for coming weeks or months will let you know.

The black stuff over glochids would be some mold of course.

[M.B]

7george, you could be right about the spines. I notice the spines remove easily and have a jacket covering them. Losing them definitely could leave a barnacle looking spot. Also, as you mentioned they could be new spines coming in. Thanks