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Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:09 pm
by Winchestercactus
Good evening,

I am wondering if anyone can give any advice on an issue I am experiencing with a handful of seedlings I planted late 2019.
In around October some of the seedlings seemed to turn white, no powdery mould etc, almost like a white skin. They’re not soft, I’ve attempted to ensure I do not over water them, the spines are strong and as it is only on a few of the batch I have no idea what’s caused it, how to rectify it, and how to avoid it happening again in the future?

If anyone has any ideas or could offer advice I’d really appreciate it!

Matt

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:12 pm
by edds
What are the seedlings Matt? Have you sprayed them with anything?

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:16 pm
by Winchestercactus
Hi Ed

In all honesty I am not 100% on the seedling ID, I bought a generic seed packet and gave it a go to boost my collection.

As yet I have not sprayed with anything, but have been looking into fungicides or plant invigorators?

Thanks

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:36 pm
by iann
Mites?

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:42 pm
by Winchestercactus
I have considered mites, especially as I think my echinopsis subdenudata is suffering from red spider mite but before I go and spray it with something I thought I’d just see what some more experienced growers/collectors thought or would do.

Do you think there’s a fair chance the affected seedlings will survive? They’re strong with no soft spots and a good spike to them.

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:48 pm
by edds
I wondered if they might be a form that goes white as it ages or if you'd sprayed it with something a few months ago which was now showing up. Sorry I can't be more help but hopefully someone much more experienced will be along to help soon.

If they're still solid I wouldn't be too worried at this point and definitely wait to see if someone else can offer some advice.

Re: Cactus seedling turned white!

Posted: Tue Feb 23, 2021 9:53 pm
by Winchestercactus
Ed,

I appreciate your advice and I’ll hold tight to see if anyone else can shed some light on the situation.

Might be worth sacrificing a couple just to see what happens if sprayed with a fungicide? I’m pretty torn by it but kind of feel I have to wing it despite reading up as much as I can.

Re: Cactus seedling turned white!

Posted: Wed Feb 24, 2021 1:21 pm
by HaoBao
I noticed the other day that I’ve got a mammillaria carmenae that has developed a similar white coating. I don’t know when it happened, it used to be green after checking old photos. From afar it looks normal, only when you look close can you tell, because it’s covered in dense spines.

I think I will un-pot mine, remove the soil and treat with hydrogen peroxide and keep it separate. I haven’t seen it on any other plants.

Would be interested to find out what it is.

Re: Cactus seedling turned white!

Posted: Wed Feb 24, 2021 6:13 pm
by HaoBao
Here is mine, don’t know if it’s the same thing

Re: Cactus seedling turned white!

Posted: Fri Feb 26, 2021 10:18 am
by Nory
I also have a mammillaria carmenae that has done this. It's also like a skin, wouldn't come off too easily when I tried to scrape it (the side of a needle wouldn't work, but tweezers did), and I damaged the plant a little in the process :sad: The most popular suggestion when I asked was that it was old mite damage, but someone also suggested thrips damage and someone also suggested scale. Never found out for sure.

But this was last year and the plant is still fine overall, even though I haven't treated it. It's near two other cacti and they don't seem to have been affected, so hopefully it's not bad news for your seedlings.

I'd also be interested to hear some suggestions!