Agave Weberi - Fungus or Scale and Treatment?
In the last week our beautiful Agave plant has acquired yellow and brown spots on the leaves. After an online search I believe our plant is Agave Weberi and I think it is either scale or fungus. Can you help me identify the problem and suggest the best treatment? I took a photo of the entire plant so you see it is protected by a wall and surrounded by cactus. It is in part shade this time of year. We don't water it. Thanks for your help.
Pima County Arizona
From your images, I'm not convinced it's scale or fungus. For one thing, you state they acquired these spots just last week. A scale would have taken several months to cover the leaves, and there would be bumps where the scale would be, rather than just spots and scars.
Nor is what I see consistent with common fungal lesions that occur in cool weather.
It is more likely to be hail damage from the inclement we've had recently, and possibly earlier in the year because of the scarring. This makes sense from what i can see because the undersides of the leaves appear fine.
Please read this publication for more on agaves: http://cals.arizona.edu/pubs/garden/az1399.pdf
If you are still concerned that it is something other than weather related, please contact the Pima County Extension office at: 520 626 5161
Laura worded this incorrectly. These spots weren't acquired in the last week. The plant has had these for several weeks. Pretty sure this is not due to hail or snow. None of the other plants had any similar spots.
Does this change your diagnosis?
In response to your follow up question, it could be the agave plant bug mentioned in the publication I attached. They shouldn't be active this time of year, but inspect the crevices or try to recall if you've insects like the one in the publication.
Do follow up with a call to the Pima office.