Friday, September 9, 2016

Learn from my mistakes #20 Agave Edema (this one hurts)...

I really wanted to blame this on the company we hired to remove the moss from our roof. Yes, as immature as that sounds, I REALLY wanted to. But, as the story unfolded, it became obvious the only one to blame...was me. And infuriatingly not because I'd ignored a potential problem, but because I'd done what I thought best to avoid it...

We've had a moss problem developing on our roof for years now, changing home insurance companies provided the impetus to finally do something about it, in fact we had 30 days to take care of it or else they were cancelling our policy. I interviewed a couple of companies and went with the one I felt had a plan to provide the least damage to the garden.

Here they are working on the garage roof, which was worse than the house roof (this surface was on the north side). I know it's not of the best quality but it's the only photo I have of the work in progress.

Here are some of the chunks of moss that came off the house roof. They're dried up and dormant.

The company did a great job of cleaning up what they could, but there are hundreds like this scattered around the garden. At least they kind of blend in with the gravel...

Being pro-active I decided it would be smart to cover the Agaves nearest the house. I had been assured they would be very careful in spraying the moss preventative (the final step, after scrapping and removing the existing moss), so it wasn't so much to keep them from getting over-spray, but rather to keep all the bits of moss and shingle grit out of them. After all I've picked out small pieces birds toss from the gutter on numerous occasions, and knew it wasn't a project I wanted to tackle on a larger scale.

I used burlap; old coffee bags and just random pieces I had laying around.

Also a sheet and an old duvet cover...

The guys who did the work were very efficient and done by noon, everything was fine when I took off the covers. Disaster adverted! (I had been dreading getting the work done, fearing the worse).

The next day when I went out to get the mail this is what greeted me. I quite literally felt like I had been punched in the stomach. How was this possible? My prize Agave ovatifolia 'Frosty Blue', ruined! Chemicals! My mind immediately went to the spray they'd used. They must not have been careful after all. Damn them!

The photo above was taken with my phone on August 17th, so I could quickly post it to Facebook (more on that in a minute). Here's what it looks like now. One of the leaves has folded back, so its damage (on the bottom side) is less visible.

The damaged tissue on the other leaves has either completely died (white) or kind of regained a bit of the "frosty blue" that makes this plant so desirable.

After first jumping to blame the workers I calmed down and looked around.

These Canna leaves were not covered — ditto for the Yucca rostrata, Amsonia hubrichtii and Opuntia — and yet none of them showed signs of damage. Perhaps something else, not the chemicals, was to blame.

Agave utahensis, tucked in next to the A. ovatifolia and also covered and damaged.

Quickly after posting photos on Facebook information started rolling in from the experts: Agave edema was the likely culprit.

I'd heard of that before, and even wrote about it. But it never occurred to me that covering my Agaves with burlap for all of 4 hours could cause it. The eventual high that day would reach 87, but the morning hours, when things were covered, were overcast to party cloudy. We had just come off a heat wave though, 94 and 98 under bright blue skies the two days prior.

Here's another piece of this (complex) puzzle. Notice the Agave ovatifolia on the far right above? Not a bit of damage, and it too was covered.

However with the single layer of "fabric store" burlap, which it turns out has quite a loose weave...

Unlike the double thick weight of the old coffee bags, which lets no light through. The flawless Agave also faces slightly north, thus may receive less intense sun?

The damage continues on the other side of the front steps...

Agave americana

Ugly. It too was fine when I uncovered it, the damage showed up later.

New growth is fine...

Minimal damage on this, which I think is Agave neomexicana (it came from an Agave rescue, with mixed up labeling)...

And nothing on it's pup.

Agave gentryi ‘Jaws’

And A. desmettiana variegata...

Agave 'Kissho Kan' is such a sun wimp that it's back further, mostly in the shade...and has no damage at all.

Before I launch into a few more random photos I want to share information from that Facebook thread I mentioned, I think it's interesting and potentially valuable. Feel free to skip on if it's too plant geeky for you! Names included because if you're an Agave lover you'll no doubt recognize a couple of them. (oh and this is just the sciencey stuff, there were also dozens of kind and caring comments on that thread from friends, while extremely important to me I figured you didn't need to read them all!)...

Gerhard Bock: Oh no, I feel so bad for you! I would be devastated. Based on my personal experience, it looks like what is sometimes described as "agage edema." People theorize it's caused by sudden changes in temperature and/or light exposure. Both might be the case here. I have an Agave guadalajarana that had the same kind of damage after being in the trunk of my car overnight.

Greg Starr: I agree with Gerhard about the "agave edema". Although not really edema, this damage tends to show up when plants are subject to unexpected shade in the middle of the day. I never really had this happen to any agaves in the ground, except A. montana, until this year. I've had it happen when taking plants indoor for shows and sales, and when transporting plants for sales. New leaves should be fine, but that damage will stay on the older leaves. Maybe it will get covered up as the new leaves grow out.

Greg Starr: Another thing that I've noticed is that plants that had been recently watered seem to be more prone to this damage than those that have been kept dry. So I try to let my plants dry out some before taking them to sales. Also, when I have spotted plants, i have never had anybody mention that they arrived with any similar damage. Of course I ship without soil.

Daniel Serrano: Money on CAM respiration being the primary culprit -- they just can stand differential cellular pressure.

Greg Starr: Aren't agaves primarily C3? I thought they had the ability to switch between CAM and C3. If CAM were the culprit wouldn't we see similar damage in cacti? I have never had any cacti show similar damage.

Daniel Serrano: True, money on c3 -- whatever their f-Ed up respiration mechanism, they just blast under disparate and seemingly inconsistent conditions.

Jennifer Zynischer: CAM fails when the nights are over 80 degrees. (piping up from Phoenix, where this happens often during our summers) No water at all during those times. Bone dry soil.

George Hull: Greg is of course quite right. The damage is permanent though. We would get this damage shipping agaves light dark light.

Greg Starr: I attribute the damage to the process of respiration being interrupted very suddenly, causing the stomates to shut rapidly and not allowing gas exchange to slow normally, thereby causing the surrounding cells to burst from a "gas overload". I think it has nothing to do with air flow, primarily a light-dark change frequently in conjunction with a change in temperature. I have noticed this happen more when transporting plants from a cooler to hotter location, but that is not consistent.

Interesting, right?

Okay just a few more photos. These little guys were covered with a single-weight, light-colored sheet, and there is no damage.

Ditto for this A. parryi...

And this NOID (but maybe one of the A. parryis?)...

Interestingly I later discovered these pups, and the container they're in, got a little over-spray on them — no damage.

And this! This little guy (Agave 'Silver Surfer') wasn't covered but rather stuck in the (dark) garage overnight and into the next morning. After all it's right by the garage and easy to move.

This showed up the same day I noticed the other damage. Again, there was no cover, just moved into a dark space overnight and into the next day (approximately 18 hours).

Finally, when I mentioned I'd heard of, and wrote about, Agave Edema this is the blog post I was referring to. I did my best to sound like I understood the condition, and I guess I thought I did, but for it to happen in the summer months just plays with my mind.

More info on Agave Edema can be found on the San Marcos Growers website here and here. Robert Muraoka writes about it here. Still want more? There's a lively discussion on the Xeric World page about whether or not Agave Edema even exists, page down to the comments from "agavemonger" to read the best feedback. And finally here's a post my friend Gerhard did about the same thing on one of his plants. At first he thought it sunburn but then Agave Edema was diagnosed.

As with all my "learn from my mistakes" posts I truly hope you do learn from this mistake. I know I have, although the differing reactions from the different types of Agaves, and what they were covered with, tells me there is no hard and fast answer. As I've said before, this gardening thing is not for wimps!

All material © 2009-2016 by Loree Bohl for danger garden. Unauthorized reproduction prohibited and just plain rude.

48 comments:

  1. Loree, thank you for sharing this. I've had an education on agave care this morning. I actually have a couple of agaves with this kind of damage, one of which I moved earlier this summer from a sunnier spot to more shade. Now I know why it looks the way it does. The other may be suffering from summer sunburn. There's a lot to learn about their care, clearly. I hope your agaves' new growth eventually obscures the damaged leaves. They are remarkable plants, well worth the trouble.

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    1. Isn't that crazy? You move it out of the sun and it gets damaged. I'm willing to wait for the damage to grow out on all but the A. americana...thinking about removing that one.

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  2. I'm so sorry for the damage on your agaves! Thanks for sharing your mistake and the facebook interchange for us all to learn from.

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    1. Sounds sappy but "if it helps just one person..."

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  3. Wow. That is so disappointing. I'm so sorry, Loree. *heavy sigh

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    1. Thank you...and your right, very disappointing!

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  4. I can still feel your pain. It's one thing when it happens to a small plant you just bought, but much worse when it's one of your favorites in a prominent spot in your garden.

    Thank you for compiling the scant resources on this issue in one easy-to-read post. A lot of people will bookmark and/or refer back to this post.

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    1. As Sean pointed out when he was here "at least they're right next to the front door..." - I am pleasantly surprised at how the A. ovatifolia is already looking better. Gives me hope.

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  5. I'm so sorry, Loree! I can well imagine how you felt. It happened to me once and in fact, in investigating the cause, I found your original blog post. In my case, I'd laid out $40 for a good-sized 'Blue Flame' agave at an Orange County nursery. The plant rode around in a hot car while my friend and I made a trip to another garden center and had a leisurely lunch. I saw the beginning of the damage by the time I got my plant home hours later (the agave was the only one of numerous purchases that was damaged) and it was more obvious the following day. When I checked in with my friend, I learned that her plant was showing similar damage. Your earlier and current posts are instructive and appreciated, although I remain apprehensive about transporting agaves any distance in the car.

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    1. Oh man! A 'Blue Flame'...that would be heart breaking. I hope you don't have to suffer it again.

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  6. Amazing information and diagnosis. What a relief that you have discovered the cause and I'm grateful you've shared this information. There's a lot one can learn from plants!

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    1. It's a constant learning process isn't it?

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  7. Some people are always attracted to the prima donnas...but I'm not naming names.

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  8. So informative and yet so sad. I'm so sorry for your agaves, but it looks to me like the damage to the A. ovatifolia isn't ruining it's stunning beauty too much. I'm having problems with some potted agaves and some dry-loving plants because we switched from bloody-hot and humid to moist, cool nights: rot. Ugh. Zone/climate denial-it can't be helped. :(

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    1. Looking at a mark on an older leaf of the A. ovatifolia, I can see just how fast it's grown...hopefully we'll have a nice long and sunny autumn so it can grow grow grow! Sorry to hear about your problems, rot is not fun.

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  9. The science-y part really is fascinating. I'm sorry for your damages, though.

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  10. Sorry about the moss and damages. Your photos are beautiful.

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  11. This too shall pass, ovatifolia will grow out of that, and you have preserved your homeowners insurance.

    Very interesting and educational discussion, and thanks for the various links. Since the problem has to do with moisture, none of that damage here. There is a suspect spot on one leaf of a marmorata with damage. It happened back in January on the cold night. Yes, it got cold one night--a frigid 38F!, so I thought it was cold damage. Maybe it is edema. I didn't cover it though, and it was dry, dry, dry...

    Also quite surprised to see Facebook actually contain something of interest (Agaves), rather than only advertisements and pictures of cats.

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    1. I wouldn't be so quick to conclude that moisture is a part of the problem, my plants were very dry.

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  12. Really interesting post Loree, thanks for all the informative detail. I only have 8 Agaves at the present and the only one I have had any issues with was 'Arizona Star',(purchased from Cistus many years ago) which has been moved around relentlessly.I finally found a good spot in the ground and I hope the older crappy leaves will be obscured by new growth by the end of next summer. I meant well, moving it into a dark garage when it rained to keep it from too much moisture, but now I know better !

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    1. Another interesting twist, that I didn't mention in the post, fearful it was getting too long anyway...is that I take some of my Agaves inside, to the basement, every fall. I guess the fact the days are shorter helps to keep this from happening then?

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  13. Highly informative and helpful post. I cover A. ovatifolia with a light sheet when we get sudden heat waves in early spring and have not seen damage. Since I have burlap coffee bags on hand to cover plants during freezes I am very grateful you took the time to explain this so I will remember to reach for the old sheets when agaves need cover.

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    1. I've used burlap successfully in the winter...perhaps because of the different light levels then?

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  14. Lots of helpful info here -- great post. Sorry about your Agave damage, but it looks like the new growth is OK? So, will it cover the damage and allow the plants to be fine over time? I remember you posting this on Facebook and all the responses. You're right--gardening isn't for wimps!

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    1. Yes, the new growth is fine and with time the damage will be less visible.

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  15. This is an excellent follow up post and so many pieces to the puzzle of leaf damage on some of my agaves are suddenly falling into place. As you know, I have to overwinter my agaves inside because of our Denver winters, so I've always felt it was sunburn when some of the leaves were damaged when they were moved outside for the summer, no matter how careful I am to acclimate them to our intense sun. I had no idea my beloved spikes are so fragile! Thanks for the info, Loree. Now I just have to figure out how to deal with the issue!

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    1. I do think what you're talking about is sunburn...at least that's been my experience in the spring. It's disheartening no matter the reason.

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  16. Really interesting and informative post. I'm sorry you had to experience it firsthand to share this with us, though.

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  17. For a newbie to agaves this is good to have on file - thanks, Loree! Otherwise, so sorry it happened :( And of course, you probably put your "best" (heaviest) coverings on your best plants: a bit of Murphy's Law there!

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    1. Indeed, why waste that wimpy piece of burlap on my prized A. ovatifolia...

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  18. Such a shame to see damage to a prized plant. Knowing it will grow out is never much comfort. Such an informative post though. We get that a fair amount even in the UK, mainly after buying plants and transporting them home. I always though it was the heat, interesting to hear it may be as much to do with light as well.

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    1. It's a strange phenomenon isn't it?

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  19. 'Arizona Star' was the one agave I lost last winter in the December Monsoon we had. I'll never leave another one uncovered outside again..... it was probably my favorite agave.

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    1. Our rain last winter was intense, I am surprised any of our Agaves made it through!

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  20. I'm still puzzled about the whole thing. I have bought or been given small "rescue" agaves in Palm Springs and shipped them home in small boxes by mail and never seen any damage, even after 3-4 days in the box. I can't figure out why I should see no damage with that kind of treatment? And I'm always moving my potted outside agaves to get either more or less sunlight depending on the season and temperature. It's all very confusing to me.
    Thanks for writing this up, Loree!

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    1. Me too (the shipping thing)...heck and the confusing thing!

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  21. Extremely valuable information because there are times when it is so hot I do cover my agaves and also when we have incessant rain as this August. I have done quite a bit of this this year and I do have a little damage. I notice at the ADBG they use shade cloth but have it up on sticks like an umbrella. That's what I need to put out there- a few old umbrellas.

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    1. I've often thought of this clear, and very "tented," umbrella I had as a kid. It would be perfect for Agave protection.

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  22. After reading all those links, I don't know why it's seemingly only me that is left scratching my head saying "huh?". It sounds like there are multiple factors under both conditions of cold, hot, wet, dry that can cause agave distress. The only common link that stands out for me is distress caused by a rapid or prolonged change in conditions. I had no idea that Agaves could be so sensitive, I've never had this happen with deliveries from wholesale growers, nor Agaves I've transported in the back of my own truck, usually draped with a plastic tarp for up to a half to full day. I have seen sunburn damage on Agave attenuata's in local heat waves, and also winter damage to Agave 'Joe Hoak' which I'd assumed was from the cold, but San Marcos Growers seems to link it with too much sudden moisture rather than simply cold damage.

    Sorry to hear of your damages, I know that would freak me out too. The only solution I can hypothesize that might have avoided such damage is tenting the cover so there was no direct contact, similar to avoiding contact freeze burn with covers in winter.

    I swear after reading all those links twice, I am no closer to understanding why it happens, except to avoid sudden temperature and sun exposure changes.

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    1. You're not the only one scratching your head David! But I think your last sentence sums it all up best.

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  23. Heart breaking! I know nothing about agaves except that they are bold and magnificent plant. Come to find out that are so fragile.

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    1. Maybe not fragile, but not without their own "achilles heel"?

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  24. I followed this event closely on Facebook as it's a learning curve for all of us. Very interesting findings and suggestions. Shame about the damage and I share your frustration you have felt when you first discovered this. Onwards and upwards now, with lots of knowledge and wisdom gained for all of us along the way!

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    1. Indeed, the only way is forward...at least the sun and 80 degree temps have returned (after a few days of cool grey drizzle). Hopefully they'll all have a chance to put on some new growth before winter.

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  25. For being so spiny, inflexible, and slow growing, agaves put on a lot of fuss under cover for a few moments. GEEZUS.

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