Sooty mould around areoles

[Roy]

Hi all,
no matter how well you ventilate, on some cacti that produce secretions, for instance ferros, black mould develops. How do you get rid of it? Pressure hoses can work on tough hard specimens if used with care but are a no no on anything remotely tender. Brushes (electric tooth brushes)
I find are difficult to get in to the spines. What do you do?

[Tina]

Hi Roy

I have been trying out 70% alcohol on a small paint brush, in theory it should kill the spores.
the other option would be spraying it I suppose & some sprayers have a jet option and a wide dispursement option

[CactusChris]

Hi Roy,
I've almost give up growing these plants - the sooty mould is almost impossible to remove without as you indicate extreme measures. As long as the sugary secretions occur the mould will grow. Fungicides will work but.....who wants to be spraying chemicals all the time? Natures answer is to remove the sugar - ants will harvest it no problem, but not usually here.

So I have no answer - this was all just to let you know you are not alone... ;-))

Best regards

Chris

[David_L]

Hi Roy

Yes it's a difficult problem. Thinks that do or are alleged to help include:
1. Yes --ventilation--- cool still humid conditions make it worse
2. Frequent spraying with soft (rain) water to wash off the sugary secretions as they are formed.
3. Cleaning with a brush and a small amount of soft soap dissolved in rain water
4. Prophylactic spraying with mycobutanil (used to treat black spot on roses). Be aware that though this works to kill the fungus/yeasts that cause the soot it won't remove existing sooty marks and can leave a visible deposit on the plant.

[MikeT]

Try spraying with water & washing up liquid, leave for several minutes to soak, then spray with clean water to rinse. On some plants gentle cleaning with a toothbrush may be needed as well, if you can get at it. I haven't tried this technique on sooty mould (must get round to trying it in the spring), but it worked well some years ago after a problem with the paraffin heater produced loads of oily soot one night. The following spring I tried this, it did the job, and various white spined & white hairy plants cleaned up really well (better than they'd been before the soot episode). I now don't heat the greenhouse, so that avoids a repeat episode of heater problems (& cheaper).

Mike T
Sheffield branch member

[iann]

I place prone plants in a location where they are accessible to ants and will get rained on during the summer. That keeps them pretty clean and if they're not tough enough to handle the conditions then I'm too lazy to keep them

[Roy]

Well thanks for all the suggestions even though one reply started to give me flashbacks! Yes Mike the soot filled greenhouse happened to me once, not an experience I would like to repeat

[David_L]

Hi Roy

This bugbear has appeared on a Glandulicactus (sclerocactus) uncinatus and Thelocactus bicolor in this last cold, greenhouse closed up, not good ventilation week. I'm seriously considering a leanto open on one side to the elements for these supposedly cold tolerant types. Meanwhile -- constant vigilance!

[Roy]

My friend digs out the gland to stop the secretions but thats on large plants it's much more difficult on the average sized plants