Hello all.

I am posting in regards to my venerable San Pedros, who as some number of members may or may nor remember have survived multiple goat attacks, who have contracted some kind of horrific fungus. Pictures attached for examples of pathology. Here are my questions for cactus-cultivators: A) Do you happen to know what this fungal assailant is? It begins as a rust-colored patch of discoloration beneath the skin, then progresses to this white, scar-like material which then develops these tiny black spots over a period of time. Also B) from my research, the prognosis isn't really good. I think I need to cull the crop and start again from all the unaffected pups I have removed from the mother-cactus -- so my REAL question is this --- think if I made this mess into a standard tea that I'd be including nasty toxins from the fungus? Should I just attempt an extraction, as yielding semi-pure mescaline would remove some or lots (or all?) of any potential fungal toxins?


Here's the story:
I've had these growing since late 2010/early 2011, and have multiplied my cacti several times now as I always had a "thing" about harvesting with intent to eat my cultivated clones... I always felt like they were still too scrappy, they need to thicken up, they're too little, etc. I basically just didn't eat them, and living in a non-native climate where it gets to zero F/ -32 C many years in the winter I have to bring them in so they wont freeze. Well, then it got to the point that I was way cluttered up with cuttings on cuttings on cuttings (I still am, for the most part). Anyway, a temporary move to another city saw me transporting all of these cacti from the old spot to the new spot. I got all but the largest four specimens and left the four cacti in my dad's care.
Well, leaving it with my dad to care fore was just pure laziness on my part, and dang It appears I am paying for it now; he left them in a window just a bit too close to the woodstove... and there was some heat damage. By the time I found them, a few days of this cruel and inhumane punishment had already gone by.
I think it was these wounds that gave an opening to some opportunistic fungal attacker... because this horrible fungal scarring is occurring, well, all over. You all can see for yourselves, it's a horror show of bad Cactus-management skills.

edit - the examples attached here are all of the late stage of this thing. I've tried various fungicides, never was able to do anything more than slow its progress. However, with a solid feeding and anti fungal sprays new growth will outstrip the fungus, so I can salvage maybe the tips on a couple of these...
I'm worried about now introducing this pathogen into the clones that haven't been exposed yet.

How unfortunate!

FWIW, I recently stopped an outbreak of the dreaded "black spot rot" in a bridge-looking specimen by spraying with tincture of nutmeg (1:2 in 80% ABV ethanol). That's possibly a bacterial disease, though, rather than a fungal one - I'm not entirely sure.

Are those off-white areas in the bottom picture spore bearing surfaces? If so, it would be a good idea to keep the spores away from the rest of your specimens at all costs. I'd swab the spore-bearing surfaces very carefully with some isopropyl alcohol to kill off the spores without disturbing them too much..

If there aren't spores forming there, I'd be somewhat inclined to say the damage looks rather like sunburn. As well, some level of woody incrustation is normal for older specimens but, indeed, it running up the whole length of a specimen like that doesn't seem right.

Hey, thanks for the reply.

Yeah, my pictures weren't really of good quality, so the detail was not really evident. The infection starts as a rust-colored discoloration, then progresses to the off-white scar tissue looking areas, which eventually begin to develop areas of dark black but tiny spots -- which I assume are the spore-bearing areas.

Any thoughts on health and safety concerns for consumption? I am definitely going to cull that big bridgesii specimen, who is by far the on that got it the most. Those four-sided pups which also got the disease were from that specimen too. :/

Probably a good idea to remove those pups while they're still alive. Those white sections look too damaged to salvage.

Ah, the rust mould infection! That attacked some of my T. peruvianus specimens that had sustained damage after freezing. I was very lucky and, much to my surprise, 5 cuttings survived. I seem to recall storing them at a cool room temperature and low (~30%) RH for a couple of months. As well, I will have sprayed the cuttings with IPA before trimming off the rotten bits and then smudged them extensively with copal.

With short-spined peruvianus at least, if you can stop the fungus when there's still about 40% of green still on the surface I'd say the cuttings are in with a chance. Looks quite humid where you are though?

Rust mold, ok, yeah that was what I was inclined to think as well. It is a real pain y'all -- if this stuff starts to get going on your cactus, don't be a slowpoke like me! Be proactive, save yourself some trouble, and cull any infected specimens. For sure.

It's been since, oh, say April that I first noticed it, and in that time it got that bad on those guys (who were the most-effected). There are a couple small ones that did have it so I'll need to get right on harvesting them.

I didn't take any photos of the harvest and prep for cooking, but underneath all of the scarring I was pleased to see that on the big bridgesii still had all of its dark green layer fully intact! However, the scars did make the process of skinning much, much more laborious than it otherwise would have been. Sooo flaky, causing the it to take at least twice as long.

edit: Oh, and as for location. . . let's just say USDA zone 6b

Ohhh man I get this with my bridgesii as well. Lost a few really nice to plants to it. I have many cacti however it only affects my bridgesii.

I’d love to have a fix for it. In my experience even if you get a new plant that shows no signs of it just being in the same area as an infected plant and your sure to cop some of it again.

The bridgesii that I have in the ground and with adequate sunlight and abundant nutrients are staving it off so plant health plays an important role. They are far more susceptible in pots compared to other cacti 🤷‍♂️

Trichos, Bridgesii especially, are calcium hogs. I have a few different bridgesii clones that give me issues when the humidity/moisture is high, which is pretty much always where I live. Something like Copper fungicide is great to have on hand for this kind of thing. It will keep the fungal infection from spreading. Its never a bad idea to spray the surrounding plants as well, as a lot of these fungal pathogens can be transmitted through backsplash, or run-off.

Many seasoned growers report that bridgesii tends to be more sensitive to excess moisture (ie. greenhouses, wet zones with little air circulation (this may even be your house), subtropics/tropics etc.) and develops these types of rots when in prolonged contact with infectious liquid against its skin. That's why I think the rots usually start from bottom up where the cutting is most likely to meet the splash of contaminated droplets during watering. Your best bet is prevention by establishing a suitable environment and ensuring a good protective layer between the stem and the soil to prevent splash. Pumice or pebbles would work well. Since these are already infected and the fungus seems to be spreading beneath the dead dermis, contact fungicides such as copper, wettable sulfur or mancozeb would be ineffective. Your best bet is a systemic fungicide for the cut you wanna save. I tried myclobutanil with somewhat dubious success and heard people praise phosphorous acid, but have no experiences with it. Most of the time when you dig into these old scabs you will see that the plant has developed a tough barrier between the healthy tissue and the rotten portions. If you leave a good safety margin between the healthy flesh and this border while cutting it our, I would not worry about the risks these infections pose on consumption. If you used fungicides that's another story and I suggest you read some toxicology reports and lotsa MSDS. I suggest you do a local dissection and see if the rot is still active at the bottom. If so just save what you can and give it the chop. I not you might be able to log it or just save the tip.

*Edit: A nute feed heavy in nitrogen will inflate the cell with water and thin the cell walls, while low potassium will prevent plants from thickening and strengthening the cell walls. The result is a plant MUCH more susceptible to fungal infections. Upping your potassium feed might help as well.

Hi guys, thanks for the replies. Sorry I'm late, college got me so distracted I haven't posted since [the semester] started (ha)...

Thanks for the nutrient tips, I will definitely be incorporating that in the next season. We're in full winter here so all the plants are inside again (the same situation that initially caused the fungus... ) . I have half of my guys under a 1000 watt (I think) HPS light (which they seem to be enjoying); the other half I have in "dormant" phase in a room that honestly doesn't get adequate sunlight. So what do y'all think, in this indoor winter phase (which can last 3-5 months here), would utilizing a dehumidifier be a good call?

Oh and I went ahead and culled a big part of my collection (all the ones that had it), or maybe cull is the wrong word --- I harvested them. Haven't cooked em yet but I have lots of material to work with now once I get it out of the freezer. I saved many of the tops though, so now I am back to having a ton of little 3-6 inch guys all over the place. Sprayed everyone with fungicide, seems to have helped.

Looking back, it does seem that most of the ones effected WERE the bridgesii, although by the time I got it under control some of the others seemed to have caught it too.

If poor ventilation is implicated, perhaps it would be worth taking a leaf out of the indoor peyote growers' handbook and installing forced ventilation (a fan or fans, presumably) for the bridgesii as well.

This winter mine are in a structure that protects them from frost and precipitation but allows a good level of ventilation all the same, without using any fans. So, a slightly draughty tent, more or less.

Best of luck, got my fingers crossed that your babies will see it through to spring safely!

Nice, ok, there is indeed a small window that some sort of ventilation could be rigged into... do you think that just a regular fan that fits perfectly with the window would work, or should I be thinking more like grow-room vent systems?

(oh and thanks for the crossed fingers my clones appreciate ya )

Sorry I dropped this thread! I hope you and your cacti are doing OK. What I meant was any kind of air circulation around the cacti such as a regular desktop fan.

I overwinter mine in a heated tent. One year that I pitched the tent on the bare ground, Spring came and it rained rained rained, but the temps were still kind of low so I delayed taking them out of the tent. The extended humidity in the tent from the rain-soaked ground caused some rot. The years they were out of the tent for several weeks in the almost daily Spring rain I had no rot problems. It seems to me the enclosed humid environment caused far more problems than frequent, almost daily rains. Ever since the enclosed tent rot year I've always put down a tarp as a moisture barrier before pitching the tent, and I time the infrequent Winter waterings with warm spells so I can ventilate the tent to avoid an extended humid environment inside after a Winter watering.

I have a fan blowing across them in the greenhouse during the day in the growing Season. It definitely helps dry them out after a watering, with the clay pots drying out even faster. The fan, along with some shade cloth helps keep the temps lower in the Summer, although I'm still looking for other ways to keep the temps down from June to September.

yeah, it seemed all clear for several months, all spring but it's been _extremely_ humid and so it never really went away. I've been dealing with that this summer, had to cull a lot of different ones... yeah unfortunately it just seems to be a part of the ecosystem here and everywhere I assume… very annoying I have one 5 foot example that I've been really trying to keep it off of you with some spots that are worrying to me… And now I have yet another issue I believe I may have over fertilized said 5 foot example. I'll provide photos tomorrow but yeah I may need some tips on that as well. I followed the instructions to the letter but maybe should've put half or a quarter of what they said because it seems to be burning (both the 5 foot bridge and a heavenly blue MG). I'm going to attempt to re-pot tomorrow I did a big flushing today, about 20 minutes of water to try to wash out the excess nutrients. I don't have the package in front of me but I remember it being a pretty high K value, will provide photos tomorrow.

Thanks

also p.s. I think my little lemon tree may also have the rust mold fungus -- gotta remember to take a shot of that too.

It seems pertinent to bump this thread since one of my specimens (a pachanoi, iirc) has developed a case of 'the dreaded beige crust'. First it had developed some black spot rot over the winter, then in summer it got spider mites in the same area. I sprayed the spider mites with neem oil in IPA which finished them off - but next time I'll use an aqueous dispersion because neem IPA does weird stuff to the cactus. As a result, the damaged area seems to have got the beige crust fungus.

In the image attached below it should be visible how the fungus is spreading through the vasculature of the areas surrounding the beige crust. This ones for the chop, methinks. I may rustle up an essential oil spray as well to see how it fares with that. Either way, I'm keeping a very close eye on it and drastic action will ensue should this disease carry on progressing.

GOA- The damage looks heat/sun caused to me. It can take awhile for the scabs to show up. I got some really bad sunburn on some of mine this year and it looked exactly like that. Some of mine got orange and black spots as the scabbing progressed, likely an opportunistic fungus attacking the damaged areas. The burned skin is extra sensitive and treating it with most things seems to make it worse instead of better. The new growth you saved should be fine though, and I think the parts you froze would be fine for tea or extraction.


DFZ- That looks spray burn from the neem/alcohol mix. The way it looks like the scabs are dripping down really makes me think this. Oil spray residue can burn cactus easily when the sun hits it. That cactus you posted the pic of doesn't look that bad tbh. I would let it grow unless it seems to be spreading or getting worse. Spider mites rarely show up or affect my cactus, usually just the very top a little. I've sprinkled DE on the tip and it has worked well for getting rid of them.



All that said, I really like monopotassium phosphite (phosphorus acid) for cactus fungicide. It's way less toxic than other systemic options, and is also a biostimulant/fertilizer for the plant.

reDeMpTion - thanks for the reassurance and tips. These scabs looked rather different from the weirdness that occurred where the spray drip down the clefts between the ribs, and it appeared on the 'north side' of the cactus after a more humid spell. Nonetheless, your observation about the drip-like form of many of them is indeed correct. Fortunately the puffy yellowing does not appear to be spreading significantly so I've got my fingers crossed for the moment that this mighty specimen will pull through its latest ordeal!

What a shame it would be to have to chop it, now that it's grown to the princely size of 4 feet (120cm) - except, of course, that I'd already been considering propagating a few more of this handsome thing. Tbh, I would dread cutting it because it's clearly going to be hard work! Veering into that tangent, the most desirable option that I can think of is getting it to pup somehow. I'm still holding out for the day when one - any - of my Trichs produces a flower.

A week later now, the situation appears to be stable and reDeMpTion's observation seems correct. Thinking back, the problems may well have started when a piece of frostbitten Opuntia rotted in the pot last winter. And thus we learn the importance of hygiene in the wintergarden (or do I have to say conservatory?)... I'll be keeping a close eye on things over the coming months. It does just get so damp here for about eight months of the year, and once the temperatures stay below 10°C - well, that really sucks for the more sensitive cacti.

Photo attached for comparison.