black scabs

[strangebrew]

I have a cutting that had some small(>1 cm),hard black scabs on the body. I presumed it might just have had something to do with sunburn but now I'm not so sure.

Out of curiosity I took them off as they peeled quite easily, expecting them to heal to the usual brown colour. To my surprise, a couple of days later, the wounds had turned black again.

I then made a new wound myself and this is healing normally. The main cut healed OK as well.

So far my collection has remained fairly clean and I would like to keep it that way. I'd rather throw the cutting than have it spread something.

Any ideas on what's going on?

[Slarty Fart Blaster]

Unfortunately it is rot, i too have had this occur but it doesn't seem to be a very infectious rot but cutting off or messing with the spots it not a good idea.

They usually appear if you are over watering, so ease back on that and let the soil get bone dry every now and then.

If it continues try take a cutting from a piece that is not affected and propagate from that.

Good luck

SFB.

[smogs]

yeah just leave it alone and they will turn to scar tissue and all will be well

they make your cacti look ugly tho

mine just got whole bunch coz of the stupid humid raininyt weather

[M S Smith]

http://plantpathology.tamu.edu/Texlab/Flow...wers/cacti.html

Soft Rot (bacterium - Erwinia carotovora): The bacterium enters tissue through natural openings and wounds. Under conditions of high humidity, the bacteria reproduce quickly, spreading to healthy parts of the plant. Diseased tissue is watery, soft, black and deteriorates rapidly. If environmental conditions turn dry, the development of the disease may be checked. The best control is to avoid wounds, treat broken surfaces right away with a copper fungicide and avoid having plants in places where humidity is high.

~Michael~

[strangebrew]

So do you think it's better to go after it and treat it, or to leave it?

[Torsten]

Originally posted by M S Smith:

(bacterium - Erwinia carotovora)....treat with a copper fungicide and avoid having plants in places where humidity is high.

This makes no sense at all. Either it is bacteria )in which case a fungus is probably the best cure ) or it is fungal and then copper and low humidity are advised.

Treating bacteria with copper is like giving antibiotics for viral diseases.

[teonanacatl]

i thought that bacteria would be as suceptable to copper as other organisms........

[smogs]

not as much so as fungi... they really dont like it

plants dont like coper much either... im not sure if level to knock over bacteria would also give the plant a bit of stress?

[M S Smith]

Torsten said:

"Treating bacteria with copper is like giving antibiotics for viral diseases."

Hi Torsten, I am not so sure of your analogy. Bacteria are living organisms and are feeding and reproducing in the process of causing soft rot. The would be considered an external parasite of sorts ON the plant itself and therefore could be effected by copper. Virus enter cells to do their damage.

I don't treat my soft rot at all and simply stop watering and try to dry the plant up.

~Michael~

[phosphene]

Bacteria dont have the penetrating hyphae of Fungi or in most cases the extracelluar enzymes that can dissolve living tissue well ahead of the actual pentrated zone

You can see this with rotting cucumbers in the fridge or in soft pears

Bacteria are more susceptible to drying out than fungi so this is always the preferred option

as i understand it copper in water forms nasty complexes that are quite toxic to aquatic life

the exact detail im sure youll find if you look into it

hence it is useful for many organisms inhabiting a moist environment

like Fungi and algae especially

but not limited in its effects to higher forms plants and protozoa.

Copper poisoning in humans is a serious issue where it occurs

so copper for cactus rot regardless ofthe pathogen is probably a good call. It may inhibit the bacteria a bit and will certainly inhibit secondary infections by opportunistic pathogens

Better than sulphur anyway which has never worked on anything ive used it for

Out of interest lettuce and carrots fed antibiotics hydroponically showed resistance to similar organisms so maybe for very precious plants some antibiotics might be in order

[teonanacatl]

 

quote:

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so copper for cactus rot regardless ofthe pathogen is probably a good call. It may inhibit the bacteria a bit and will certainly inhibit secondary infections by opportunistic pathogens

 

Better than sulphur anyway which has never worked on anything ive used it for

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copper based fungicides work on more things then sulphur based ones do, they are more toxic but while useing safe spraying techniques will cause no damage.