Hi, John

Maybe this is edema. I have had a problem with edema on a lot of my plants this year after a wetter than usual summer. I know we are now in the dry season, but it is still showing up on a few of my Aloe plants. My Agaves look pretty good.

I have had fungus on my Agave desmettiana in the past. I sprayed the plants with a copper solution and that took care of it. It will not damage your plant.

Those are my 2 ideas. Good luck!

thanks for the input. I posted the pictures on several "expert" sites and asked a couple nursery owners in the area. No one is certain, it seems to be a tossup between a fungus and scale, with the consensus leaning towards scale, I've treated the scale with horticultural oil and a systemic. I'll hit it with a fungicide as well, since the plant is looking worse not better. Thanks for the thought. We've had an incredibly dry fall, virtually no rain for the better part of three months and the cactus bed does not get watered.

scale I think, have you tried looking at the bumps with a magnifying glass, scraping with a fingernail to see if there is a creature underneath the surface? It looks good otherwise, like you are doing everything right. 3 months of dryness is nothing, they can go much longer than that.

thanks so much for your input. I've asked a few other people, both locally and on a couple of "expert" sites, and while there isn't total consensus it general agreement is scale. I've treated both with horticultural oil and with Merit systemic. So let's see what happens.

I did look at it with a loop and scraped a bit but didn't see anything. I didn't really look that hard since I didn't know that you could actually see the "critters." Probably to late to see anything alive at this point, at least I hope they're dead, but I'll know to look for critters moving next time. Thanks again

My Agave americanan mediopicta alba had this last year. Edema occurs when the roots of the plant are absorbing moisture from the soil but the leaves stomata are closed (due to the weather conditions and the plant being covered reducing photosynthesis) and the plant is unable to transpire at the normal rate. The internal water pressure builds up to the point that the bottom of the leaf surface ruptures and creates “water-soaked blisters” these lesions then turn into the yellow/brown “scab-like” areas.

From the San Marcos folks…”We likely compounded the situation by covering our crops of Agave 'Joe Hoak' with frost protection cloth (Agryl fabric) the nights after the rain because of frosts warning associated with the tail end of the storm. This would have trapped moisture around the plants and also limited transpiration the following day when the plants were left covered.” (San Marcos)

Santa Barbara's Pest Control Advisor Robert Muraoka wrote an article on this phenomenon… “The symptoms begin as small water soaked blisters which continue to swell, burst, collapse and then turn tan or brown in color. This is not a fatal disease but the damage is unsightly. Although the blemishes on the leaves are permanent, new foliage will be free of the disease, unless the same environmental conditions that caused the disorder are repeated.”

thank you. Can this happen during very dry weather. We've had virtually no rain since early September. The "bed" that the plant is in is a specially made cactus mix of sand, perlite with a bit of potting soil. It is extremely well drained and gets no irrigation at all.

you are not likely to get it during dry weather, especially since you are not irrigating that bed.

the San Marcos article refers to "the bottom of the leaf surface", and the OP's photo is of the top of the leaf surface.

John I hope the Merit works for you. I had an infestation of scale on my K. luciae. The flapjacks were flopping! It was hard to find the scale because it was between the leaves. Bayer systemic worked for me, so Merit should work for you.

I have seen a lot of plants here in Cape Coral as well as in Ft. Myers that had edema - new growth is looking good since we have dried out some. I also have seen a lot of scale this year. Those gardens made me feel a little better about fighting the same things, but not much.

Weird year for sure! Again - Good Luck!

@John are you in the Tampa area? Just curious because if you are, St Pete has a Saturday morning market, and Mitch Abrom usually attends with his partner and plants. One of his specialties is succulents, he was the local pres of cacti succulent(can't remember official name), and he is really neat to talk with and very helpful. I post here partially out of embarassment because of my ignorance, and my family has local raw honey right next to him, and I don't want them to realize how many succulents I've "rescued/adopted", whichever sounds better ;) I joke a lot but He would be extremely helpful with your succulents and agave. Hope this helps! I agree about a unusual dry fall/Florida winter. I had planned to use rain water for mine, but it didn't rain like normal!

Thanks, not Tampa, Windermere, just outside of Orlando. I love to go to plant fairs, markets, St Pete is about 75 miles away so a bit of a jaunt. How large is this weekly market?

Grr I just deleted my message I spent to much time writing here...anyway here is the shorter version Depending on your time and to do list it is a really nice in my country background opinion a large market and beautiful surroundings, also the Dali museum is right around the corner and the beach (: I didn't realize till earlier my loaner replacement phone was changing Mitch Armstrong to Mitch Abrom, close though ;) lol. Anyway he and his partner/significant other also have a blog which would give you a better idea of whether would want or need to go to the st Pete market : www.heyplantman.blogspot.com

let me know how it goes! Sincerely Mary

I'm in tampa and growing a lot of agaves in the landscape and the only problem I get is a soft white scale...not cottony cushiony scale, same MO but smaller. I use Merit a drench. That being said I have not really looked close enough to see the kind of damage that you have. It may be there but I haven't noticed. So I guess what I am saying is that the scale may already be gone and what you see is the damage.