Tuesday, January 31, 2017

Agave pumila rot—can it be stopped?

Once upon a time, I had a perfect agave I loved very much. While it wasn't exactly rare, it was definitely uncommon, especially at this size. Its name was Agave pumila:



I bought it in March 2016 at Grow Nursery in Cambria on the Central Coast of California and planted it in the ground in the smaller of the two succulent mounds that replaced our front lawn.



I love how beautifully it contrasts with the variegated octopus agave (Agave vilmoriniana 'Stained Glass') behind it.


My Agave pumila did great all summer and fall and wasn't fazed by the freezing temperatures we had in December (San Marcos Growers says it's hardy to 20°F). 

But earlier this month I noticed that one leaf in the middle (not one touching the ground) was softer than the others. Warning bells went off in my head--rot!--but I was hoping it would stop. But, just like the rain, it didn't.

On Saturday I pulled off the leaf. It actually came off easily and cleanly, but it exposed this:


Yep, that was my reaction as well.

I sprayed the wound with a fungicide I had on hand (Daconil; active ingredient: chlorothalonil), hoping for the best but not expecting it.


A day later the brown area looks even darker:


At this point, I don't know what else to do, other than leave it alone. I will definitely cover the whole plant when the next rain storm comes (Thursday) to keep it as dry as possible.

The thing that annoys me more than anything else is that there is nothing to be learned from this. I suspect that somehow the leaf sustained a small injury, allowing rot to set it. Shit happens, as they say. I should also add that I've had agaves that looked far worse, with rot right in the center, that pulled through in the end and outgrew the damage. So I'm not giving up quite yet.

And if this Agave pumila dies, I have a smaller one ready to take its place:


It's still in the juvenile stage, with a tighter rosette and stubbier leaves. As the plant ages--slowly, very slowly--the leaves elongate and the rosette becomes more open. There is no record of Agave pumila ever having flowered, so the only propagation source are the occasional offsets.

In Agaves of Continental Northern America, Howard Gentry speculated that Agave pumila might be a natural hybrid between Agave lechuguilla and Agave victoria-reginae. This agave is only known in cultivation; no plant has ever been found in habitat. The juvenile stage lasts about 8-12 years, or possibly indefinitely if the plant is confined to a small pot. In a larger container, and definitely in the ground, the plant transforms into what you see in the photos above.

18 comments:

  1. That's a shame, and it's the biggest A. pumila I've seen so far too. That's the only thing, even if you didn't do anything once fungus sets in it just does its thing. Fingers crossed, who knows...

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    1. Fungus is an insidious thing. I guess I need to let it run its course, what is left after my fungicide application.

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  2. Hope it doesn't get worse. If it does, perhaps it will force the plant to produce offsets? Wishful thinking...

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  3. I had to cut some leaves off an octopus agave. Their cupped shape was holding rainwater for days and a fungus set in. Might have to yank it entirely, so we'll see. I just saw a mature A. pumila recently and really admired the form they ultimately achieve. I've always passed them up in small sizes. Thank goodness for your foresight to have a small one in the wings to take over! It does look glorious fronting 'Stained Glass.'

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    1. I think it's the combination of rain and cold. I've noticed brown spots on my Agave weberi 'Arizona Star'. If they start to spread, I'll have my knife handy (sterilized, of course).

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    2. My beautiful "Arizona Star' bit the dust last winter in heavy rains. I yanked it mid-winter from it's well drained, large pot and brought it indoors, but to know avail. I have two small pups that have struggled since. It was one of absolute favorites. Not to be a downer here, Gerhard.
      I'm unfamiliar with Agave pumila: really nice specimen.

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  4. Have you considered you might have brought back agave weevil, and if you dig farther in it will be obvious? You DID bring it back from SoCal, where it is a problem. Sue

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    1. Sue, I'm fairly sure it's not damage from a weevil since it started with one specific leaf. Even now, the center is firm, other than the damage you see in the photos. I'm not even sure agave weevils are much of a problem outside of Arizona...

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  5. How disappointing. I've much less experience than you in dealing with problems like this. FWIW, when confronted with what appeared to be rot on an Agave 'Mateo' I'd planted in the ground, I pulled it up, removed all the leaves below the rot and planted the remaining core in a pot - it's been in the pot for months now and appears to be recovering.

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    1. I've done what you described with good success BUT not at this time of year--with more rain in the forecast. I think I'll pull it out tomorrow before the next rain storm arrives on Thursday. See Daniel's reply below.

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  6. Y'all are getting more rain than normal. I have a similar issue here in NC for certain species that like it dry dry. What I have found effective is the following protocol:

    1. dig it out.
    2. treat bacterial infection (low tech = cinnamon powder, high tech = chems).
    3. dry it out unpotted.
    4. put it into a soil mix that has something like 0-5% organic -- I lean toward 0% organic media.
    5. Wait.

    I have resurrected plants more far-gone than this using this protocol.

    Soil media: 33% coir, 33% calcined clay, 33% pumice.

    I know that's a bummer, really nice specimen. Good luck!

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    1. Daniel, great info. I will do what you described. I *do* want to save it.

      One question: You think it's a bacterial infection rather than fungal? Cinnamon is supposed to work on both so it probably doesn't matter.

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  7. Oh wow Gerhard, how crappy is that ? My Az Star (which finally got moved to the ground last summer) is not looking too hot either-it had no problems with the frost but the rain has not made it happy.

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    1. Mine absolutely hated the heavy November-December rains we had in 2015. Upped and died on me.

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  8. Hope you can save that beauty. x Pumila are extra sensitive to water sitting at the base of the leaves I have read more than once. I would only add to Daniel's excellent advice to replant after recovery on enough of a slope to tilt the plant so water drains out.

    Mine in the round is at quite a tilt (> 45 degrees) on a steep slope. Seems okay. I was worried about 5 days of heavy rain we got, but then we got Santa Ana winds and 8% humidity and everything dried out dramatically.

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    1. in the ground not the round! typos this week.

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  9. I feel your pain, you know I do. Only thing is I'm growing my treasured Agaves where I know it's risky, you're not. I hope it recovers, the digging it advice is great.

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