Encephalartos Natalensis x Arenarius root rot, help please!

[Merlyn]

Help me save this E. Natalensis x Arenarius! I lost a 3" caudex Arenarius earlier this year to root rot, it did not like being in the ground with a cool and rainy winter. I dug this one up because it had been progressively losing older fronds without expanding and appearing to work on a flush.

The root structure is fairly large but has very few white roots. Most are older and grey. The main root section is not rock-hard, it is somewhat "squishy" to the touch but not totally sponge-y. I sliced off a section of the root that felt softer, and it was wet and mushy inside. It didn't smell rotten, but this looks like root rot to me.

I was planning on progressively slicing off the lower section of roots upwards until I hit solid roots. But I'm not sure how to tell the difference between good and bad root tissue. If it's orange and squishy it's bad...and hard and white it's good? Or is the inside of the root structure not always hard like a carrot?

Any recommendations for treating the cut areas? I used Hydrogen Peroxide for crown rot on palms, and Banrot systemic. I also have sulfur powder and Alliette (aluminum triphosphate) on hand.

Closer view of the root structure, there are a few small openings in the main body of the roots.  It is somewhat squishy but not completely mushy.

I sliced off a small section here.  Orange and mushy inside:

And this is a cross-section of the sliced off part.  Also orange and mushy, but doesn't smell rotten...yet!

[Tracy]

2 hours ago, Merlyn said:

Any recommendations for treating the cut areas? I used Hydrogen Peroxide for crown rot on palms, and Banrot systemic. I also have sulfur powder and Alliette (aluminum triphosphate) on hand.

Fortunately for me it isn't a problem I have ever encountered, not that I haven't killed a few cycads over the years.  I just have no experience with catching them at this stage of rot and trying to revive them.  The only thought is that once you determine the appropriate topical treatments, I would say plant it in straight pumice if it's available.  It's the fastest draining media you could use and least likely to collapse, pack and become too dense to drain well in the short and medium run.  Good luck.

[Merlyn]

12 hours ago, Tracy said:

Fortunately for me it isn't a problem I have ever encountered, not that I haven't killed a few cycads over the years.  I just have no experience with catching them at this stage of rot and trying to revive them.  The only thought is that once you determine the appropriate topical treatments, I would say plant it in straight pumice if it's available.  It's the fastest draining media you could use and least likely to collapse, pack and become too dense to drain well in the short and medium run.  Good luck.

When I've had to transplant a few others of a similar size (E. Aemulans x Lehmannii) the whole underground root section was hard, like a carrot.  The Ae x Lehmannii had a pretty deep taproot that snapped off, and the end (about 1.5" diameter) was definitely rock solid in the middle. 

In your experience, is the root section just below the caudex always rock hard?  The part I sliced off of this Nat x Arenarius feels and looks like a cooked sweet potato.  It's similar in appearance to the crown rotted orange birds of paradise that were dying off in my front yard a couple of years ago.  I don't want to slice off anything useful, but this part looks just like rotting mush to me.

[Merlyn]

So I did some surgery this morning.  I sliced off the bottom side roots and they were all orange cooked-sweet-potato mush.  So I sliced off about 5" below the caudex and it was maybe 30% clean and healthy tissue.  The rest bubbled up furiously with just a few drops of hydrogen peroxide:

Progressive cuts up the stem towards the caudex were all still mushy at varying amounts:

And my last cut at the base of the caudex is still somewhat rotten:

At the moment the prognosis isn't great...

[Merlyn]

I soaked the cut end of the caudex in Daconil for ~20 minutes and am letting it dry out now.  Chip Jones posted a photo below of a cut root structure of a healthy cycad.  The center area is the vascular bundle.  Note no orange areas, an indication of root rot.  My poor waterlogged cycad's chances of survival are pretty low.  I'm in the process of digging up and potting up others in perlite/Turface MVP with a small amount of local sandy soil.  That means all my Arenarius and Horridus, along with hybrids like Nat x Horr and (Alt. x Woodii) x Arenarius are all going back in dry pots for the summer. 

[Cycadsavy]

On 6/14/2021 at 7:48 PM, Tracy said:

Fortunately for me it isn't a problem I have ever encountered, not that I haven't killed a few cycads over the years.  I just have no experience with catching them at this stage of rot and trying to revive them.  The only thought is that once you determine the appropriate topical treatments, I would say plant it in straight pumice if it's available.  It's the fastest draining media you could use and least likely to collapse, pack and become too dense to drain well in the short and medium run.  Good luck.

Tracy,

I just lost a Hewson Horridus today to far advanced root rot.  The fronds were all green, but loose and wobbly, upon further inspection and tugging on them, they all popped out due to a completely rotten caudex.

Trying to keep this from happening again, do you recommend pumice over perlite for drainage?

Nick,

[Tracy]

15 hours ago, Cycadsavy said:

Trying to keep this from happening again, do you recommend pumice over perlite for drainage?

I haven't had issues getting pumice so have used it because its a little heavier so keeps the pot and plant more stable, but I don't know that one is better than the other from a pure drainage standpoint.  Reading posts here, it is apparent that there are regional availability issues that drive a lot of what people use for a good draining mix.  I don't recall what most folks in Texas are using but a perusal of past posts might help you with what other people in your area have found to be the most available.  If pumice is readily available, I would probably just stick with it and if not, you can always rephrase your question for some fellow Texans to respond.

Just a couple of questions about your E "Hewson" horridus, was it in the ground or pot and was it traumatized by your freeze this last winter?  Is it possible that it just never recovered from a cold exposure last winter and is now showing the damage?

[Merlyn]

20 hours ago, Cycadsavy said:

I just lost a Hewson Horridus today to far advanced root rot.  The fronds were all green, but loose and wobbly, upon further inspection and tugging on them, they all popped out due to a completely rotten caudex.

Trying to keep this from happening again, do you recommend pumice over perlite for drainage?

I'm not really sure what material drains better.  It could be a tossup between perlite, pumice, and something like fired clay pebbles (Turface MVP).  I'd guess they all drain pretty similar, but one type may retain more moisture than another.  Turface MVP is billed as absorbing water, so it might not be a great choice for plants that must stay really dry.  I don't really know if perlite and pumice retain moisture...that's a really good question!

Unfortunately the originally posted Nat x Arenarius died of rot, as did several other similar types.  I lost an Arenarius, Altensteinii x Lehmannii, Horridus and (Alt x Woodii)x(Arenarius x Tri) all this spring and summer.  Another Horridus x (something big and green) is likely to die too.  All died of a similar root rot up into the caudex.  The dry types (Arenarius, Horridus, Trispinosus) all seem to dislike our daily thunderstorms.  Most have done fine in pots with mostly perlite for "soil" but suffer and rot and die in the ground.  Lehmannii seems ok in the ground, as long as there's no supplemental water (drippers, sprinklers, etc) and it's in a relatively "high and dry" area. 

I planted a 4" caudex Trispinosus in the front yard in October, it just started flushing a couple of days ago.  I'm hopeful that it'll be ok there, since it's in mostly sand and the ground slopes away.  I'll find out in a few months if it's happy there!

[Cycadsavy]

8 hours ago, Tracy said:

I haven't had issues getting pumice so have used it because its a little heavier so keeps the pot and plant more stable, but I don't know that one is better than the other from a pure drainage standpoint.  Reading posts here, it is apparent that there are regional availability issues that drive a lot of what people use for a good draining mix.  I don't recall what most folks in Texas are using but a perusal of past posts might help you with what other people in your area have found to be the most available.  If pumice is readily available, I would probably just stick with it and if not, you can always rephrase your question for some fellow Texans to respond.

Just a couple of questions about your E "Hewson" horridus, was it in the ground or pot and was it traumatized by your freeze this last winter?  Is it possible that it just never recovered from a cold exposure last winter and is now showing the damage?

We’ll, it was potted.  Generally, I’d bring it inside during rain showers, but several weeks ago it stayed out overnight during a multi-hour rainstorm.  This was a day after a watering as well.  In addition, I think the soil had too much organic at about 50/50 organic to inorganic ingredients.

It was next to a standard Horridus that is still okay, but that Horridus was planted in a mix with about two thirds to three quarters inorganic, with the inorganic made up of pumice and perlite.

Live and learn, my mistake.

Thank y’all,

Nick

[tinman10101]

i would go with tracy's recommendation of pumice but if that is not available you can use dry stall NOT STALL DRY.  this is readily available at feed stores for horses.  i use both interchangeably ...