Cactus and Tender Succulents forum: White threads on roots???

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Name: Paul
southern California
Zone 8B/9A
Region: California Herbs
cahdg6891
Aug 10, 2017 8:28 PM CST
Hi everyone, I am repotting a bunch of cuttings I started earlier this year, but the last two I have unpotted have had thin, white strings almost like dry threads of paper on the roots, some spines, and bits of soil and bark below the soil level. Is this fungal growth of some kind or is this a symptom of root mealybugs? There is no white residue left stuck to the pots themselves, they are completely spotless except for dust and a few dusty perlite streaks that brushed right off. Looking through the roots, I don't see anything that looks like mealybugs and I have crumbled some between my fingers to be sure it's perlite and not a bug. Some bark pieces were completely covered in these threads. I have ceased repotting and left the two I have found so far sitting out until I know if this needs to be treated or if it's nothing.


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Name: Thijs van Soest
Mesa, AZ (Zone 9b)
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mcvansoest
Aug 10, 2017 8:49 PM CST
Many cacti will make a really fine network of thin threadlike roots in addition to bigger roots. To me it looks like it could be the start of those, but it is hard to see/say with complete certainty.
Name: Paul
southern California
Zone 8B/9A
Region: California Herbs
cahdg6891
Aug 10, 2017 9:52 PM CST
Other than the white threads, there isn't anything else wrong with them. They are either still plump from being watered about a month and a half ago or so, or growing. They all look healthy and they all have nice little root systems. Some of the other ones I unpotted had a few of these threads on the insides of the pots after I emptied them, but nothing sticky or anything. There wasn't any white residue or anything else on the bottom of their containers or poking out of the pots either, just some small cobwebs from little spiders underneath.
[Last edited by cahdg6891 - Aug 10, 2017 9:53 PM (+)]
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Name: Daisy I
Reno, Nv (Zone 6b)
Not all who wander are lost
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DaisyI
Aug 10, 2017 9:56 PM CST
To me. it looks like a plant grown from a cutting (offset) that was planted too deep.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost
Name: Paul
southern California
Zone 8B/9A
Region: California Herbs
cahdg6891
Aug 10, 2017 10:17 PM CST
Yes, I have some other ones that I planted too deeply as well, some even deeper than this one I am embarrassed to say. Hilarious! *Blush* Would that cause it to grow these? The light was fading, but I couldn't find anything resembling a mealybug on any of them. Unless they can be smaller than is visible with the naked eye Confused
Name: Thijs van Soest
Mesa, AZ (Zone 9b)
Lover of wildlife (Raccoon badge) Lover of wildlife (Black bear badge) Bee Lover Bookworm Adeniums Enjoys or suffers hot summers
Cactus and Succulents Container Gardener Hummingbirder Xeriscape Region: Arizona Region: Southwest Gardening
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mcvansoest
Aug 10, 2017 11:06 PM CST
Honesty the more I look at them the more they seem to be integral parts of the root system. That you find them on the inside of pots from other plants seems to confirm that. Those fine root systems are usually an indication that the plant is settled in and growing well. When a plant goes dormant it will let these roots die off since they are relatively easy to re-establish.

I see no reason to worry at this point in time. Stick them back in soil before these roots die.
Name: Paul
southern California
Zone 8B/9A
Region: California Herbs
cahdg6891
Aug 10, 2017 11:40 PM CST
That's a relief, I'll repot them straight away. I saw all the white threads and wondered if perhaps I had had root mealybugs sneak in. I've read about them but never seen any before so I wasn't sure.

Whew. Thanks all!
Name: Baja
Baja California (Zone 11b)
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Baja_Costero
Aug 11, 2017 11:34 AM CST

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Root mealies should be relatively easy to identify based on the size of the actual insects inside all the cottony thread. You can squeeze one between your fingers and feel it pretty easily. In fact I do that whenever I suspect mealy bug activity, because then I can confirm that I removed a bug, not just a wad of the cottony stuff (with a toothpick usually). And that it's history. Smiling
[Last edited by Baja_Costero - Aug 11, 2017 12:21 PM (+)]
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Name: Bob
The Kau Desert, Hawaii (Zone 12a)
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OrchidBob
Aug 12, 2017 1:08 AM CST
I have seen the white hairs on several of my plants too.
It is known as mycorrhizal fungi.
they are good for plants as they help get nutrients to the roots.
it is a symbiotic relationship where they both benefit.
Name: Paul
southern California
Zone 8B/9A
Region: California Herbs
cahdg6891
Aug 13, 2017 12:38 AM CST
I'll read more about that, that sounds fascinating. I remember reading that Pachycereus pringlei has some form of fungi or bacteria on its roots which can actually break down rock, but I didn't think that any form of beneficial fungi would find a dry pot sitting out in the baking hot sun to be a very good place to be. Pretty cool!

Baja, I plucked off probably ten bits to see if any were anything mealybuggy and crushed them between my fingers and they all crumbled to perlite dust - I've never seen root mealybugs before and only remembered reading that they left white stuff everywhere. Having to constantly deal with spider mites, gophers, and ground squirrels is starting to make me jump at shadows and see possible pests everywhere Hilarious! Rolling on the floor laughing
Name: Baja
Baja California (Zone 11b)
Cactus and Succulents Seed Starter Foliage Fan Xeriscape Container Gardener Bromeliad
Hummingbirder Native Plants and Wildflowers Garden Photography Region: Mexico Plant Identifier Forum moderator
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Baja_Costero
Aug 13, 2017 3:13 PM CST

Moderator

It's good to be alert, regardless. You'll miss fewer things that way.

Root mealies tend to like it when the soil is dry for a lot of the watering cycle. Here they tend to be most problematic in late summer and early fall, and greatly reduced or eliminated when it rains. I've seen them on agaves and a few other plants, usually accompanied by ants. You can pretty effectively drown them to mimic the natural effect of rainfall. They're among the easiest bugs to eliminate once you identify them. Way easier than gophers. Smiling

We have gophers and ground squirrels but no spider mites, owing to the coastal humidity. The mammals start to get real hungry/thirsty this time of the year, and they'll be snacking on the garden more and more until it rains again.
[Last edited by Baja_Costero - Aug 13, 2017 3:18 PM (+)]
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