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Is this Rust or scale or other?

Posted: Tue Mar 05, 2024 3:06 pm
by PlantLife74
I keep my desert cacti in the basement overwinter, and stop watering from October to April. Recently I noticed one of the cacti had orange color spots all over it. I have no idea how long its been like that, but reminds me I should check my cacti more closely over the winter! It doesn't appear on the other cacti, but I've isolated the one but havent done anything with it yet. Would like any confirmation so i know what i need to to get for treatment. Also Im still unsure what species if cacti it is. The images may be a bit grainy as I had to zoom it with my phone. The cactus is still small which I wonder if that made it susceptible. Thanks for checking!

Re: Is this Rust or scale or other?

Posted: Fri Mar 08, 2024 6:05 pm
by PlantLife74
Desert Plants of Avalon was able to look, and she suspects its spider mite damage. I couldn't see them with my eyes but the damage is there. She recommends isopryl alcohol spray every 2-3 days so the substrate does not continuously remain wet. later when it warms up, I could use neem oil dilute and horticultural soap but less frequently.

Re: Is this Rust or scale or other?

Posted: Sat Mar 09, 2024 1:32 am
by edds
Mites is a reasonable guess. Just make sure you don't leave the plant or compost wet if it's still cold where you are.
The plant looks like some form of Gymnocalycium to me.

Re: Is this Rust or scale or other?

Posted: Sat Mar 09, 2024 2:04 pm
by mcvansoest
If it is spider mites, you better start checking the plants you kept around this one. They spread pretty easily and quickly...