The not-so-good, the bad, and the ugly

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We need to talk about some bad things today. I usually focus on the prettier sights in the garden, but, as I'm sure you know only too well, life isn't all roses and rainbows. Sometimes it's rats and hollowed out oranges:

What you see above is what our entire orange tree looks like this year. My wife managed to rescue three (!) oranges from the voracious teeth of “our” roof rats. They're a problem all over town—the City of Davis even has a page dedicated to roof rats on their website—and I was far too naive to think we could coexist with them. I don't mind letting them have a few oranges, but not an entire crop! Next year, I'll be much better prepared.

UPDATE: A friend thinks squirrels could be the culprits, too. Or a combination of rats and squirrels. We do have plenty of gray squirrels, so anything is possible!

Speaking of bothersome animals with sharp teeth, the *$※⁉⁂s aren't satisfied with a fruitarian diet. I came across this sad sight recently:

×Mangave 'Pineapple Express' with the tender new leaves in the center missing

As aggravating as the rats are, most of the damage in the garden can't be blamed on them. Winter has done its share, even though it's been a mild one. Emerging aloe flowers are particularly sensitive to the cold even if the plant itself is perfectly hardy. In the examples below, notice the tips that look like they've been freeze-dried—it's because they have:

Aloe aculeata

Aloe petricola

Some plants got nipped by the cold because I'd forgotten to cover them:

Zamia furfuracea, a fairly tender Mexican cycad

Epiphyllum 'Queen Anne'

The other epiphyllums are fine. And really, it hasn't been that cold. We had a couple of nights just below freezing, but I guess that was enough for these tender beauties.

The biggest problem this winter has been rot. The rain we've had this water year has been sporadic but often heavy—over 5 inches on October 24 and 25, and another 5 between December 13-17. While January hasn't brought any rain, we've had quite a few misty nights, resulting in a persistent blanket of moisture on plants that would rather be dry.

 So far, I've found rot on two agaves. The first one is Agave wocomahi. It grows at high elevations in northern Mexico and can take quite a bit of cold, but it appears to be sensitive to water sitting in the center. I first noticed signs of crown rot in early November and immediately applied some fungicide. That seems to have done the trick. The rot has stopped and new leaves are emerging.

Agave wocomahi

 The second rot-afflicted agave is Agave gypsicola (not to be confused with Agave gypsophila). Agave gypsicola is a newly described species ( 2019, Abisaí García-Mendoza) from Oaxaca. It's related to Agave guiengola, and just like that species, it's not very hardy. My plant has quite a bit of rot, both on the lower leaves and in the center. I don't know if it's cold damage or simply too much exposure to moisture. As with Agave wocomahi above, I've sprayed the affected areas with fungicide. We'll see what happens. I knew from the get-go that this species might be iffy here in Davis and may need to remove it altogether.

Agave gypsicola

Agave gypsicola

 Similar patterns on some aloes and mangaves:

Aloe vaombe (the smaller of two)

Aloe africana

×Mangave 'Fiercely Fabulous'

×Hansara 'Jumping Jacks', a trigeneric hybrid involving genes from Agave pablocarrilloi, Agave macroacantha, Manfreda maculosa, Polianthes tuberosa, and Polianthes howardii. Polianthes is the tuberose. All three genera are closely related.

 I try to bring as few plants inside for the winter as possible, but desert roses (Adenium sp.) can't survive outside in a climate where winters are wet and cool. This year I waited too long. My adeniums (I have three) got rained on in October when they were already partially dormant. As a result, they simply couldn't absorb the moisture and started to rot. Ironically, in warm/tropical climates like Thailand (the epicenter of adenium production and hybridization!), they will happily take all the water they can get and never go dormant.

Here's an Adenium arabicum; the center is soft, about to turn mushy:

Adenium arabicum

Another Adenium hybrid (Adenium arabicum × crispum) is gone as well, but my 2nd Adenium arabicum looks to be OK—knock on wood. I find adeniums very challenging to keep alive: They need to be dry when dormant, but if kept too dry, their roots will die. 

 Last but not least, something truly ugly:

Agave verdensis

This nasty spectacle is scale infestation of an Agave verdensis. I'd ignored this problem far too long; I have no excuse, just the usual lethargy.

If this were a common species, I'd have chucked everything in the yard waste bin. However, Agave verdensis is rare, both in habitat and even more so in cultivation. Known as the Sacred Mountain agave because it's found on Sacred Mountain south of Sedona, Arizona, Agave verdensis was formally described in 2013 and is one of the cultigens created 700-1000 years ago by pre-Columbian people living in what is now Arizona. For an in-depth treatment of these domesticated agaves, check out Ron Parker's excellent book Chasing Centuries.

Since I didn't want to lose this Agave verdensis, I separated the three plants in the pot (the original mother plant, plus two pups) and washed them in a bucket of soapy water. After letting them dry for a day, I sprayed the top and bottom of the leaves with neem oil and potted up the three plants in pure pumice. The plan is to move them into cactus mix in a few months and drench the soil with a systemic insecticide to get rid of any remaining scale. I did try to scrape off as much of the unsightly deposits as possible; what's left is simply cosmetic, and the new leaves should be clean.

Agave verdensis after cleaning

Sorry for so much gloom and doom. This is not a subject I enjoy dwelling on, but it's part and parcel of gardening.

© Gerhard Bock, 2022. All rights reserved. To receive all new posts by email, please subscribe here.


  1. It's always good to be reminded we all face gardening challenges. Fingers crossed your ailing plants recover.

    1. I agree! We (or at least I) tend to think the grass is greener elsewhere, but we all have our share of trials and tribulations.

  2. Ouch! Rats have gone after the Mandarin oranges here in the past but we've been lucky with the navel oranges. I've had more problems with rabbits, which seem to eat everything (including Astelia!). I now have a large number of wire cloches spread throughout the garden to fend them off but that strategy only works with smaller plants. I haven't seen any damage from the December rains with my agaves but, based on your experience, I'll give them a closer check. I hope the agaves you've treated come through!

    1. We don't have rabbits, fortunately--or gophers, like many friends of mine in the Bay Area.

      No more rain in the forecast. I may have to start watering my potted plants soon!

  3. I have grey squirrels too , but I must say they never seem to go after anything in my garden -thank god. I think you've actually had a worse winter than I have -and we've gotten down as low as 28 more than once. I put a frost blanket over 'Moonglow's blooms and so far so good. I had to look up Sacred Mountain -I didn't recall such a place from back in the day when I was a Sedona resident, I see it's between Sedona and Camp Verde. I would love to go there and see the Agaves in situ ! I wish you success with your abatement measures.

    1. I hadn't covered any of my aloes. The flowers on all my Aloe 'Moonglow' are OK, zero damage. Ditto for A. cameronii, capitata, and many others. No rhyme or reason that I can discern.

      Agave verdensis is named after the Verde Valley. I'd love to see it in habitat also. I was going to spend a few days in Sedona in March 2020 but had to cancel that trip because of COVID.

  4. Weather-related damage is heartbreaking but expected when zone boundaries are challenged. What I find particularly horrifying is the state of your orange crop! I have no idea how you are going to fix this problem. I'd want to move :-O

    1. I'll be doing a lot more rat trapping in the months to come. That's the only thing I can do, seeing how poison is not an option.

  5. The lethargy thing is a problem here, too. I have a box of rat traps waiting and I do nothing.

    1. I usually do nothing until I spring into action and try to overcompensate, LOL.


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