Black Rot and Mancozeb

[strangebrew]

Depends on what the other cacti are. Other vulnerable types are listed in this thread but if you haven't any of them I wouldn't be too concerned.

I don't think it can be successfully eliminated altogether - whatever you do. Mancozeb certainly seems to keep the rot in check though. Recently during some humid weather I was lucky enough to notice the tell-tale bumps starting to occur before they actually blackened and broke. A spray of Mancozeb stopped them in their tracks and they got no worse.

BTW I cut into this specimen and noticed the spots. Any ideas?

I've only ever seen something similar once before and that time it seemed to be a rot that started from an infected base-cut and it travelled to the areoles and the end was not pretty.

The upper left hand spot is a healed black-rot blemish on the outside.

[Rev]

yeah i get the spots sometimes

This years been good so far for the rot

anyone tried bordeaux mix?

i wonder if slightly higher interstitial concentrations of copper would inhibit the fungus?

im going to run a trial soon using potassium fertiliser (sulpahte of potash) and a contol to see if it encourages resistance

there must be some factor because amongst my clonal cacti i have some that come down hard and die and then ones right next to it that are unaffected

i practice good hygiene and now simply trash andy infected plants rather than trying to save, and selectively propagate the healthiest seedlings and clones but with past experience there must be some ways to enhance herd resistance even by a small margin. Potassium has shown excellent field results in control of plant fungal pathogens in veggies and ive alway noticed how much tougher and robust my other plants are after potash applications

[Darklight]

Migod that black death is quick!

I left my Eileen cuttings out overnight- two at most- and then moved them away next day. Now my short spined pach ( I think that's what it is ) is completely covered in black spots! I'll Mancozeb it and see if it recovers.

One question: does this mean all cactus either 1) in proximity or 2) in the yard are now in quarantine? I'm assuming resistant species can still harbour spores which will contam someone else's collection if I were to trade them?

Edited November 24, 2005 by Darklight

[Darklight]

Anyone?

[Amulte]

id say its similar to humans and cancer. we dont need contact as we are all suseptable to it. id say the black death in cacti is similar.

i havnt had black death but i have seen it. but have not seen anyone take it to a microscope. i think that needs to be done 1st b4 we can solve it. id 1st, then solution.

[Happy Cadaver]

Amulte's right, we would need a positive ID to work out if it is a bacteria or fungus, maybe rev could culture it?

Overhead watering and water splash from pot to pot seem to aggrevate it and spread it.

[strangebrew]

http://cactusclinic.telenet.be/ca_bipolaris.html

It's a fungus.

I left my Eileen cuttings out overnight- two at most- and then moved them away next day. Now my short spined pach ( I think that's what it is ) is completely covered in black spots! I'll Mancozeb it and see if it recovers.

That does seem fast - did you touch them both?

One question: does this mean all cactus either 1) in proximity or 2) in the yard are now in quarantine? I'm assuming resistant species can still harbour spores which will contam someone else's collection if I were to trade them?

Unless the spores were transferred manually I can't see how they would be infected. Getting a few photo's up would be good just to see if we're all talking about the same thing.

This was caused by overhead watering I think.

But this is what I think of as 'black rot' that appears in humid weather.

Edited November 29, 2005 by strangebrew

[Flip]

I remember reading the name of the actual fungus a couple of years ago

or fungal/bacterial complex that infects the plants.

in one of the forums... God I wish I had preserved some of those old threads.

here's some info;

http://ag.arizona.edu/gardening/news/azdai...pear_spots.html

the fungal spores we're on any of my seeds that I germinated.

and well, I've never had a case of this black spot attack any of my plants

until I had a few trades some into my collection a few years back

that we're all suffering with every break in the skin from being jabbed with a spine

turning into a dark boil.

fortunately, with my climate, everything is very controllable

and I feel that it eventually works itself out of the system.

bright light & moving dry air - may be the best preventative here.

maybe some exposure to UV might help a bit?

[Darklight]

That does seem fast - did you touch them both?

Can't recall, but it was def the closest to the cuttings and I fidget a bit so prolly...

Unless the spores were transferred manually I can't see how they would be infected. Getting a few photo's up would be good just to see if we're all talking about the same thing.

I'll do that in the next coupla days. While the rot seems to be all over it, it doesn't appear to be killing it yet, maybe it's immune, or developing an immunity... it has heaps of light and fresh air

Thanks for all your help with this everyone

[Rev]

Most of my trichs ahev partial resistance to the rot

that is while sections can be killed off the plants usually survive and regrow once the infect limb is cut away

the more tolerant ones scab over if kept dry and cordon off the fungus no sweat

Scops, Omar pachanoi and a late macrogonoid were the most susceptible in the collection

even tho the scops fare badly the other 'spiney scops' or 'cordobensis ' types seem virtually immune

removal of heavily infected plants

dry air sunshine and a surface application of mancozeb are the best

i do my best not to cut away rots unless i have to as it cretaes lesions for secondary infections

i thought the agfent was helminthosporium cactivorum

ahhh

synonyms.....

useful INFO

http://cactusclinic.telenet.be/ca_bipolaris.html

http://mrec.ifas.ufl.edu/fdacs/Cir191.htm

http://www.speciesfungorum.org/Names/Names...RecordID=259256

as heartbreaking as it is this fungus is everywhere

no point growing clones with poor resistance unless you intend to dose heavily with systemics - in which case you cant eat the fruits...