CactiGuide.com

Not sure what I'm dealing with here. Very much appreciate your help!

Looks like scale. Try to detach or scrape these out to confirm.

I was thinking those are water spots like what was posted recently where it was explained it is a function of over watering.

hiawog wrote: ↑Fri Feb 10, 2023 3:53 pm Not sure what I'm dealing with here. Very much appreciate your help!

See this first:

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

Like 7george said, try to detach or scrape out some of the trouble spots. If you do have a scale problem, the best long-term solution is with an Imidacloprid soil soak. Unfortunately you won't be able to do it until after the growing season kicks in.

The humidity in your local climate isn't doing you any favors either -- what you're up against is something called plant edema. (I have the same humidity problem in my little corner of L.A.) The following article explains it well:

https://thesucculenteclectic.com/unders ... ucculents/

Soil-based mixes are still being used by many growers in the hobbyist community, but that's "old school" and IMO not the best way to go these days unless there's a very good reason for needing soil in the mix. If you haven't seen it before, check this out:

viewtopic.php?t=47632

I have a feeling that you're growing your cacti in a soil-based mix, so if that's the case, I think they'll do much better if you move them to a soilless mix.

If it is scale it spreads fast so Quarantine the plant until you can treat it. Imidacloprid soil soak should do the trick but like others have said wait until Spring which is maybe a month away in your climate ?

Thank you all for the help!!

7george wrote: ↑Sat Feb 11, 2023 12:17 am Looks like scale. Try to detach or scrape these out to confirm.

Yes, I can detach them, so I'm thinking scale too. I'm used to scale being white so the red dots threw me. These red ones seem to preferentially attack my matte-skinned gymnos, leaving nearly everything else (including the glossier members of the same genus) more or less alone. Thanks!

Steve Johnson wrote: ↑Sat Feb 11, 2023 4:31 am I have a feeling that you're growing your cacti in a soil-based mix, so if that's the case, I think they'll do much better if you move them to a soilless mix.

Thanks for your advice. I use different media depending on the type of plant I am growing, and I have experimented with soilless mixes. I typically get the best results when I use 15-20% of a finely-screened and properly-aged leaf mold compost, but to each their own. My less-xeric gymnos in particular seem noticeably healthier more organic, richer mixes.

keith wrote: ↑Sat Feb 11, 2023 3:34 pm Imidacloprid soil soak should do the trick but like others have said wait until Spring which is maybe a month away in your climate ?

Yeah, exactly. We aren't quite there yet.

hiawog wrote: ↑Sat Feb 11, 2023 9:35 pm I use different media depending on the type of plant I am growing, and I have experimented with soilless mixes. I typically get the best results when I use 15-20% of a finely-screened and properly-aged leaf mold compost, but to each their own. My less-xeric gymnos in particular seem noticeably healthier more organic, richer mixes.

The thing is that when we use unsterilized soil in our mixes different pests and infections can invade cultivated plants.