Candicans trouble

[MadridPeter]

Folks my candicans has black sap between a few ribs..it's not oozing and is hard...is this a sign of s bacterial problem?? Can anyone confirm they have experienced this and know what to do? ...the candicans in question is showing growth and is not looking stressed..can anyone help?

[rsales3]

A couple of things to check for, has the sap continued to spread? Will it scrape off? Will it wash off? Get a closer look with magnifying glass, does it appear to have any tiny bugs in it? Did any tree sap or other flower sap fall on it? A picture is worth a thousand words.

Could also be the cactus trying to heal after an insect attack, the epidermis could have oozed fluid that has become dirty?

I've not had the black sap problem but similar sticky stuff that was mealy bugs, they do omit a sticky protective cover at times.

Good luck.

[hegar]

I also have been thinking about what could be causing the appearance of "black sap" between some of the cactus ribs. An external injury would most likely not produce anything but a small quantity of clear sap or - in the case of some Mammillaria spp. - a milky white sap. If there were a bacterial rot infecting your plant, the liquid oozing out could be brownish. However, then it would most likely cause a quick death to your plant and the affected area would be soft and somewhat discolored. When aphids feed on a plant, they excrete a sweet liquid called honeydew. This liquid will attract ants and more often than not will also be colonized by mold fungi with dark colored spores and spore-bearing structures. This condition is named "sooty mold" and has a dark grey color.
Either way, a black sap between the ribs is not a good sign. In order to figure out what to do, you need to find out, what could have caused that sap to appear.

Harald

[MadridPeter]

I think it may be overwatering...I read the care instructions on llifle.com and it says only water moderately and in hot weather as candicans tends to get black rotted spots and fungal disease otherwise ...the black points between the ribs are not soft and cannot be scraped off..although weather is heating up here in Madrid Spain and is dry so I thought I could water the cactus like the others..maybe I shouldn't deep water it..I mean water until water exits the drainage holes in the pot ..the plant is large enough and does seem to remain plump even without any water for 4 weeks