Really interesting work Crypto.

Outstanding work Crypto. Those pictures are fascinating, you can actually see where the vascular tissue has fused and it even appears as if it has grown from the pereskiopsis into the scion !! really interesting stuff.


I can definitely see bacteria near the union, and by looking at the vascular tissue it is easy to see how it "could" be transported to the surface.


Food for thought:

Could it also be possible the cause of the rot near the union is due to the superior rot resistance of pereskiopsis. What I mean is this. Pereskiopsis love wet feet and this causes us give it an abundance of water, now regardless of whether there is bacteria in and around the roots pereskiopsis just never seems to rot. Now if the pereskiopsis was to inadvertantly transport some of the bacteria along with nutrients and water up to the scion could this also be a cause of the problem ??

Any ideas ? As Crypto more questions than answers ?

A good question Lachy, and one I can't really answer except to say you are correct. Pereskiopsis has extreme resistance to all types of rot whilst Lophophora does not.

You normally attribute hardiness and resistance to rot based on the climate of origin of the particular species. For example if a species grows (and thrives) in an area with a high annual rain fall you would assume the plant has a good resistance to a wide variety of bacteria.

Pereskiopsis are native to Mexico which depending on location averages about 400-700mm per year. Out of interest Sydney is between 1500-2200mm per year. So I guess the rule above does not apply to Pereskiopsis.

I have no knowledge regarding the biology of each plant, which I guess would be need to really get a good understanding.

It is possible to rot Pereskiopsis. ( ).

It's just incredibly difficult.

It's hardy to other extremes too, like drought for example. It's capable of surviving 2 years(sic) without water, right Crypto

p.s very interesting photos too crypto.

Well, a further update...

The graft continues to grow, and the orange patches don't appear to be growing in size. However, there does appear to be a few more of them. So, as a last resort I've made a paste of copper oxychloride and liberally painted the whole plant:



Hopefully this does the trick.

Slightly off-topic now... It's been interesting to see how the pereskiopsis has pumped up the scion so that the morphology of the plant has visibly changed. The scion was taken as an offset of a caespitose L. williamsii that displayed fairly typical williamsii rib formation. The scion now has significantly less-clearly defined ribs.

can he breathe?

He seems to be okay.

I'm impressed at the resillience of this graft. It's still cranking out pups all over the shop. If I can nail this little issue before the summer, I'm eager to begin grafting a few pups. My only concern is that it may open the main plant up to rot, resulting in its total loss.

Well, it seems the copper oxychloride is doing the trick... or at very least, is holding the orange rot at bay. The patches seem to have stopped forming and some even seem to be healing, leaving minor scars.

That looks better Lachy.

i know how much of a pain this orange rot can be, i just lost a small grafted Ortegocactus to this, not a huge loss as the plant the offset came from (also grafted) does not have the rot. and self-rooted ortego is A-ok.
and a pere grafted Turbinicarpus polaskii la bonita seedling also.

this problem seems to peak in winter IME, possibly due to less regular maintenance on my behalf. problem is if i keep plants completely dry = spider mite
or slightly moist (like mist spraying to keep down forementioned mites)= orange rot.
still its strange how one plant out of 5 identical species all grafted on the same stock species and under the same conditions, pots located right next to each other will develop the rot whilst its siblings are fine.

I've since given the loph another coat of copper oxychloride and I think I may now have knocked the orange rot problem on the head. The intense treatment seems to have no side effects on the plant, despite my initial concerns that it would scar the skin. It's not the prettiest solution, but if it prevents the loss of a nice plant, so be it.

In the meantime the loph is absolutely pumping out new pups. I'm now torn between letting it form a clump or grafting the pups to fresh stocks come summer. Decisions decisions...

Well, it seems that the orange rot has returned, and again, I'm painting the afflicted parts with copper oxychloride paste. Unfortunately, about all this does is keep the rot in check; it doesn't seem to cure the problem, not to mention the fact that it is pretty unsightly in itself. Has anyone come up with better long-term treatments?

Alright, I might just throw my few cents..

First I have won over orange-rot in two occasions, I sprayed it with a combo of 2 fungicides + 1 insecticide, actually the first time I used commercial chemicals for my plants. It was also lopho on pere. One of them survived and is still alive, and I keep stealing his pups for further grafts, and in the other occasion the pere collapsed soon after rot was healed and I had to transgraft all pups, but it worked and they are all alive and have not showed orange signs since... All of the pups I have grafted to other stocks are most from these two -formerly infected with orange rot- grafts, but I have seen no sign that the disease propagated with the pups.

Regardings lopho caespitosa, kada will have more to say and show, caespitosa are said to pup so much they are a bit 'useless' and not pretty after a while. I suggest you go ahead and graft some more. You have possibilities of forming a orange-rot free graft, as people say it might be hard to get it off lophos...

Crypto's photos are impressive and revealing too. Thanks for the sacrifice mate!

Now for my own theory, or what I thought till now, and to be honest I did not change my mind, nor do I believe that this rust we all seem to be familiar with is the same single pathogen all over...

I have had those lopho on pere grafts catching 'orange rot' after getting wet after sunburn. It's also possible to happen by getting wet after mite damage and I have sure seen it after fungus gnats little wormy larvae have chewed grafted seedling of an astro asteria.

In all those occasions I thought it's orange rot that took advantage of the hole in the skin armour.. and wetty situation...

Orange spots might form in the scion union base, as a result of a poor sterilization techniques, but who knows if they can enter the scion from there? I know that in pereskiopsis, some pathogen can travel down the vascular ring, not sure if this is orange rot, probably so...

I will be putting photos one of these days...

Another similar mystery and even more so is the notorious 'black rot', common with Trichocerei.

I posted my own adventures with a photolog here if you wanna check it out!

http://forum.auscactiforum.net/specialist-cultivation-f31/grafting-advantures-with-lophophora-pereskiopsis-orange-rot-ao-photo-heavy-t909.htm