Black patches at the base of each agave leaf

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cricket2008
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Black patches at the base of each agave leaf

#1

Post by cricket2008 »

Sorry if this is an issue discussed in the past but I couldn't find anything that looked quite like this problem. The plant has been in place for about 1 1/2 years and these patches appeared after only a few months. They appear on most (but not all) leaves after they mature, so they are only visible on the lower leaves. The black patches eventually become so thin that the leaf droops; then I lop them off. A local retailer suggested they are caused by pollen from a neighboring Live Oak tree getting stuck at the base of each leaf then rotting when there is rain. However, the neighbor who owns the Oak also has an agave in her yard that doesn't have this problem. Any ideas? Thanks in advance.
Agave problem.jpg
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Gee.S
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Re: Black patches at the base of each agave leaf

#2

Post by Gee.S »

Welcome to the forum, cricket. Hailing from AZ, I don't see that kind of thing much, but I'll guess you hail from a somewhat soggier locale. Looks like fungus/rot from here, an affliction caused by excessive moisture. The Agave shown is famously more tolerant of moisture than many others, so it might have been worse. That's a really tough Agave (A. vivipara), so cut the moisture down, and it should be fine.
Agave
"American aloe plant," 1797, from Greek Agaue, proper name in mythology (mother of Pentheus), from agauos "noble," perhaps from agasthai "wonder at".

"Some talk the talk, others walk the walk, but I stalk the stalk"
cricket2008
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Re: Black patches at the base of each agave leaf

#3

Post by cricket2008 »

Thanks Gee.S; I'm in sw Florida where we do have a rainy season, but we're dry a lot of the time too. My landscaper (who has never seen this problem before) told me not to water the succulents unless we got into a severe drought situation, so there is no moisture on which I can cut back.
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Gee.S
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Re: Black patches at the base of each agave leaf

#4

Post by Gee.S »

Improving drainage by raising the bed a few inches may help.
Agave
"American aloe plant," 1797, from Greek Agaue, proper name in mythology (mother of Pentheus), from agauos "noble," perhaps from agasthai "wonder at".

"Some talk the talk, others walk the walk, but I stalk the stalk"
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Spination
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Re: Black patches at the base of each agave leaf

#5

Post by Spination »

If you are wanting to do something, rather than watch and see...I'd give it a spray with a fungicide. I use LiquiCop, but there are others which should also be effective.
cricket2008
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Re: Black patches at the base of each agave leaf

#6

Post by cricket2008 »

Spination, thanks for your suggestion. I'll give it a try.
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Spination
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Re: Black patches at the base of each agave leaf

#7

Post by Spination »

You're welcome. If it weren't for my use of LiquiCop last winter, I'd have suffered severe losses. We had what seemed like endless wet, and an explosion of aracnose was halted as soon as I realized it was happening. The scarred leaves don't heal, but the devastating progress of the disease ceases, and eventually affected leaves are replace by future growth.

PS If it's effective for aracnose, I'd trust it to deal with any fungal malady out there that attacks agave or aloe...
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Re: Black patches at the base of each agave leaf

#8

Post by Desert Dawdler »

I thought I’d share my experience in case anyone else has thise issue in the future since I had a similar issue. I had this happen with one parryi truncata (four other truncatas in an 8 ft radius were unaffected), leaves first looking sunburnt at the base, then turning dark, with symptoms progressing from the outside of the rosette in. It turned out my husband was spraying the canes of a newly planted ocotillo with the hose and this little guy was getting hit with the overspray, 2-3 times a day.

Since I knew it had been getting a lot of overhead water, the tan to black looked very anthracnose-esque, and I happened to have a jar a Thiomyl, I decided to try and save it. I removed every leaf that had even a hint of of color change, AND the next set after that to be certain I had caught everything even before it was showing at the surface, cleaning the shears with Physan after every cut (although alcohol would probably work fine too). I mixed up a double stength batch of the Thiomyl and did a thorough foliar and soil drench. I was sure it was a goner, but it actually worked. It still looks a little odd 7 months later since it hasn’t grown out enough to replace all of the missing outer leaves, but there’s been no disease reoccurence.
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