Black death and bridgii's

[darkhorse]

I've lost two to this bastard of a disease and am losing the battle with a third. All my other columnars seem to get it and recover easily but bridgii's (except my 2 monstrose, which seem to get it everywhere and yet recover easily) just get progressively worse. I keep all my cactii outside and am thinking this fungii(?) starts at the crown from water pooling, and then slowly rots the bastards from the crown down.

Anyway my question is this third bridgii is losing its top inch, should I just sacrifice the crown and chop it or will this make it worse, I've taken all bridgii's undercover and deprived of water but its still getting worse , wht can I do to save the buggers???

[oxydiser]

I have had my first run in with the 'black death' over the course of the summer... it seemed to arrive on an eileen cutting. It has had a breakout on a few of my cacti (all bridgesii) and slowly spreads for a week or two, after which the cacti seems to mount a defense against it and 'walls' off the infection.

Alas I am in perth and I have been withholding water for the infected plants...apart from that I cannot offer any further advice but I'm sure someone else can... I hope everything turns out for the best darkhorse

[reshroomED]

... it seemed to arrive on an eileen cutting.

Was this cutting from me?

Rarely get rot here, and only then on exposed cuts that aren't airing properly.

Definitely clean when I send them.

Eileen is very disease-resistant. Yet to get any infection in over 15yrs, and she's seen some brutal storm-damage in high humidity and self-healed.

If it is one of my cuts that you're referring to, please inform me.

ed

[strangebrew]

Chopping down to good tissue will help if the plant is in a dry enough environment to be able to heal, otherwise if you really want to try and save it use Mancozeb. It's been good here rot wise lately but if I've had to I've started using a fine paintbrush to dab on Mancozeb, rather than spray and cover a plant needlessly with excess.

I think the rot is everywhere, it's just waiting for the right circumstances to break out.

Would it be true to say that Perth has had a more humid summer than usual Oxy?

[Rev]

black rot isnt always lethal. in fact most often its not

if its really fast then chop it. if it isnt then put it somewhere dry and leave it alone. it will heal itsef most times

i dont have it as much this year

partly cos the weather is drier, and part cos as the planst get older they arent as affected

seems to be a correlation with fertiliser

more fert equals higher susceptibility. as tissue ages it seem to harden up against it

the most susceptible species ive found are scops. it can kill them very quickly

all teh really fat trichs are a worry . terscheckii too

but pachs and peru seem quite resistant, briudge less so although amongst seedlings some never get it, some get it bad and so get culled

other time where i have 50 clones next to one another one gets it and collapses while those around it are untouched. so much for equal susceptbility among clones. there is much more to this than we know yet

also i know for a fact my WA sourced pachs had it b4 comeing east cos they were packed inside boxes and furniture and when they emerged they had lesions

i had never seen it expressed in perth b4

there is also a strong correlation with humidity.

ive seen it on eileen once or twice but shes never ever succumbed or even sufferred. very water tolerant that strain is.

mancozeb is quite effective against it if used topically. up to you though

it is used on food crops but still isnt nice, always use PPE and obey the label

[Rev]

oh yes

every rot that is black and causes death isnt the black rot

there seems a quorum of agents rather than just one that gets around

[strangebrew]

Have you noticed any difference btw symptoms? If so what are they?

If black rot is due to fungal spores I'm wondering whether an increase in susceptibility is due to a decrease in skin thickness i.e. maybe bridgesii have thinner skin. If this is the case applying sulphate of potash could help as this is known to increase cell wall thickness in plants.

Edited April 11, 2007 by strangebrew

[ThunderIdeal]

good idea strangebrew, i'm also interested in this fertiliser correlation.... will report back.

seems to be pretty bad in brisbane, not surprisingly.

[Evil Genius]

Black soft Rot is caused by the bacterium Erwinia carotovora. It usually doesnt kill plants and fertilized plants are more vulnerable to this disease. Just keep away the water as long as you can. If it doesnt heals, cut it away. Some plants are more likely to suffer from black rot infection. It´s probably some kind of genetic vulnerability. bye Eg

[strangebrew]

Erwinia does seem the most likely,

"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."

but for some reason Mancozeb works better than copper. I was under the impression that for bacteria this shouldn't be the case, that copper should work just as well.

Also the rot can occur where there are no natural openings or wounds. It often starts around the tip or between ribs where skin tissue is the weakest. Could a fungus and a bacteria possibly be working in tandem?

Whatever the case, if I suffered from it badly I'd try growing the plants hard with little nitrogen and treat them with a lot of potassium 4 times a year.

This is a good article that talks about black spot in succulents and how trying to pin it down has proved impossible so far. http://www.cssainc.org/content/view/290/212