I have more than one Opuntias with sooty mould due to a sticky weeping from their areoles. I carefully checked for aphids/scale insects/caterpillars and other culprits but there are NO bugs on the Opuntias. I wonder what the cause of these secretions could be. Does the Opuntia secrete a honedew like the Ferrocactus? Any ideas about what to do?
Many thanks for your comments.
Opuntia weeping
Opuntia weeping
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Re: Opuntia weeping
My Opuntia ficus indica does it too.
Re: Opuntia weeping
Normal. Lots of cacti do it. My Glandulicactus have nectar running all down the plants right now and I can't persuade the ants to come and take it away 
--ian
Re: Opuntia weeping
Wouldn't you rather buy a hive of bees to do that? You could sell honey to earn money for more cacti.iann wrote:Normal. Lots of cacti do it. My Glandulicactus have nectar running all down the plants right now and I can't persuade the ants to come and take it away
Re: Opuntia weeping
Not too bad then... only a nuisance about the sooty mold. I tried spraying a copper based fungicide with little improvement. What could be done?
Re: Opuntia weeping
Is the nectar what attracts cochineal bugs? I'm not saying this cactus has them, but I was just wondering.
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Steve Johnson
- Posts: 4526
- Joined: Thu Nov 03, 2011 4:44 am
- Location: Los Angeles, CA (Zone 10b)
Re: Opuntia weeping
I was wondering about that myself. I got a new Tephrocactus articulatus var. diadematus in mid-March, then a few weeks later I found this little drop of goopy charcoal-colored stuff on the bottom stem. Not knowing any better, I automatically assumed that something was wrong. Haven't seen it since, but good to know that it was normal. With that said, I'd like to know if the nectar could lead to pest problems in case this needs to be treated.iann wrote:Normal. Lots of cacti do it. My Glandulicactus have nectar running all down the plants right now and I can't persuade the ants to come and take it away
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
My location: Los Angeles, CA (Zone 10b)
Re: Opuntia weeping
Pest don't need nectar, they just tap directly into the plant. The nectar does tend to go mouldy and black in more humid climates. Ants are attracted to it and this may be the main purpose. Could be a nuisance in a greenhouse but at least they stop it going all black. Bees aren't in tune with it at all, they only go for what's in the flowers.
--ian
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Steve Johnson
- Posts: 4526
- Joined: Thu Nov 03, 2011 4:44 am
- Location: Los Angeles, CA (Zone 10b)
Re: Opuntia weeping
My overnight humidity is staying around 70-80%, going down to 30-40% in the day, so that fits the bill. Are there any problems with sooty mold beyond just being unsightly?iann wrote:Pest don't need nectar, they just tap directly into the plant. The nectar does tend to go mouldy and black in more humid climates. Ants are attracted to it and this may be the main purpose. Could be a nuisance in a greenhouse but at least they stop it going all black. Bees aren't in tune with it at all, they only go for what's in the flowers.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
My location: Los Angeles, CA (Zone 10b)
Re: Opuntia weeping
"Sooty mold" does not lead to any severe plant disease. There are a number of fungi that are opportunistic and will grow on the sugary exudate.
The only two things that are objectionable are the unsightlyness and - in case of a severe presence of this problem - perhaps a reduction of the plant's ability to photosynthesize. So I would go ahead and periodically wash the sooty mold off.
Harald
The only two things that are objectionable are the unsightlyness and - in case of a severe presence of this problem - perhaps a reduction of the plant's ability to photosynthesize. So I would go ahead and periodically wash the sooty mold off.
Harald