Fungi name Guesses?

Experiencing with only one rose type cutting in a grow chamber a seesaw battle with a virulent fungi l have never seen before (claim gardens are fungal disease free to my eyes except occasional late season PM and odd hp rust).

This fungi attacks new growth and then wilts and destroys it within less 3 days.

Long hair like encircling growth in a fuzz ball on shoots-and new leafs (couple of mm or more). Original color white grey turning brown with age.

Touching “hair” ball causes what l call an explosion of “a spore dust cloud”.

Only thing not javexed at start of season with a solution was the cuttings. Another type of rose cutting in chamber not affected.

As a strike back, chamber and pots re-javexed with a solution and washed with hot water, soil dumped and replaced with new bought soil (seedling mix). Only item not javexed solution treated was again the cuttings. Respawned like a bad video game of the WD in a couple of days.

Any guesses? Or leads?

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White mold?

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I would agree that your suggestion is the best candidate.

Its not powdery that l am use to, or downey mildew in my opinion (no blotching).

Especially when a week or so ago l found a couple of small black bumps … thought they were bugs but they failed the squash squishy test.

Until today did not have another candidate and black bumps clinched it.

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What you describe sounds to me like it could be botrytis, although a photo would help. I’ve never seen anything like sclerotinia on roses (although I have seen it on beans–nasty stuff). Botrytis cinerea can be a problem outdoors on rose flower buds and even flowers, especially under certain (wet) weather conditions, and I get it from time to time on rose cuttings in very humid rooting environments–usually on old (dying) parts and on tender new growth. It usually ceases to be a problem once humidity drops, and can be managed temporarily by removing the infected parts, although some fungicides might be used as well. If the cuttings have new growth, they might be ready to start transitioning out of the very humid rooting environment/chamber anyway; if they have new growth but you’re sure there are either no roots or insufficient roots, then I would just pinch off and remove/destroy any infected new growth. Pinching off new growth is no problem because there should be vestigial buds waiting in the wings to replace anything lost. Gingerly removing the cut growth that’s laden with spore-producing fungus and then torching it with a flame before too many spores can get away can be surprisingly therapeutic.


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Sclerotinia sclerotiorum_roses

Hello RikuHelin!
my first spontaneous thought also went in the direction of botrytis. Just a side note to the suggestion of @lee_hull to Sclerotinia sclerotiorum: It certainly attacks roses but causes Rose Bent Necks on Commercial Cut Roses (Rosa hybrida L.)

In case of closer interest, pls have a look at the attached actual publication:

If I come up with another idea, I’ll let you know.

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Thanks for the alternative contender … l’ll wait until the latest infection gets more pronounced and get a photo. I may have over emphasized the “brown” color change as the infection ages.

Still lean to white mould because of the black lymps found though agree not much reference to it attacking roses. Looks like a dandelion seed head.

Though “noble rot” would great coincidence since there is a bottle of ‘05 Chateau Y’quem across the room from it plus a couple lesser Sauternes.

Nov 11

Not rampant and dense all consuming infection, but still a chronic on one rose cutting type. Take todays photo and imagine leaf enclosed in fruiting stems so it barely visible.

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Hello RikuHelin,
initiated through your image I have studied again some photos on the internet (pls see comparison based on the figures next to the links). Gray Mold seems to be the fungal disease that fits both your description and your photo.

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Excellent Roseus … except for the cutting … l agree as pretty definitive photos of the fruiting heads. As well down to the conditions in chamber match down to condensation and temp ~ =/< 20C.

Other rose type cutting (Auli) in same chamber is healthy and named a gallica cross.

Infected one is surprisingly to me, a northern European (xcross?) robust growing species (Olkala) though not sure if gallica or whatever a turbinata (sic) is.

Friend reports their Olkala cuttings have no issues. It then leads to me speculating it is pure grow chamber conditions.

Will increase ventilation, heat and hope residual spores don’t head to my cross chambers. Will go non chemical in containment strategy … except for javex rinse spray if required.

Wish l could blame it on residual spores on sauterne bottles :slight_smile:, unlikely as they are suppose to be sterilized at the time.


Yep, that is definitely definitely bot rot, and there’s nothing noble about it (at least not in roses)! The good news is that it doesn’t have to be a serious problem for cuttings if you don’t let it go completely unchecked–I prefer physical controls, only to be followed by some sort of chemical intervention if absolutely necessary. Organic copper sprays might be an option, although you would need to read the label carefully first, and that will obviously vary from country to country. I don’t believe there is enough information available to assign general botrytis resistance or susceptibility ratings to different rose cultivars, although variability certainly does exist. I had a seedling this season whose flowers all struggled to open in moist weather outdoors because of botrytis, even though almost no other roses had similar troubles… needless to say, it isn’t going to make the cut.



Opening all vents to drop humidity - as measured by lack of condensation - and turning the heat mat up to give~20C inside chamber resulted visual disappearance of fungus.

Soil surface kept damp.

Foliage on surviving cuttings show no visible indication of infestation and “clean green fresh” looking.


Thanks and Congratulations, RikuHelin! I’m delighted, that’s really good news.

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