exotic plant, exotic pest

The upper canopy of my two plants of Aloe barberae (aka A. Bainesii). The left one is the larger, typical form. The one on the right is the dwarf form from Mozambique. The one on the left is the one affect by aloe mite.

I’m heartbroken that one of the two big tree aloe in the front yard is under attack by aloe mites, the scourge of many aloe growers. The succulent expert at one of my local nurseries just shook his head when I asked for anything that would make the mites go away. Of course I ran to the web for advice. Discussions splattered all over the charts, from guardedly optimistic to “throw the thing in the trash.” I started to uncover several references to the syndrome that the aloe gall mites generate as “aloe cancer.”

The best discussion I encountered I’ve seen so far is at XericWorld forums, where the whole range of opinions gets expressed by a number of experts. The thread has lots of photos of infected plants and of the mites themselves. Growers expressed success with insecticides (even though mites aren’t insects). Others had zero results even with dedicated miticides. Most people recommend plant-surgery, and one person treated affected areas with bleach.

A newly developing gall.
One of the galls produced by the plant in reaction to being attacked by Aloe mites.

Sunbird Aloes, a commercial firm in South Africa, the land of aloes, recommends a completely different treatment: formaldehyde applied to the gall.

There’s also an informative page hosted by Michael J. Green hosted at the Gates Cactus & Succulent Society [ here ]. The author here points out that the gall is produced by the plant in reaction to a chemical produced by the mites, a compound similar to 2-4-d, one of the main ingredients in the infamous Vietnam War herbicide Agent Orange.

Closeup of another of the galls on the trunk.

Most of the treatments are intended for spot treatments when only part of the plant is infested. But my poor plant has a major infestation all over its main trunk, and that’s been affecting the growths farther up. It’s been in gradual decline for several years, but it’s going downhill quickly. At first I thought it was gophers eating the roots, or the renters next door stopping watering of their lawn and the aloe roots that extend under it. But I’ve finally figured out the awful truth. Even the plant seems to realize its distress since it’s starting to shoot new growths from near the base of the trunk.

I step back and try to be philosophical and maybe even marvel in my grief that such tiny, nearly microsopic creatures can take down such a large plant. It’s all a part of the cycle of life that we celebrate with the seasons and the changes plants go through. Only with something tree-sized I was hoping for something that would outlive me, not a twenty-year relationship that would end in tragedy.

The end of one of the leaves being produced at the base of the plant. I'm not sure if this might be early signs of mite damage or a bad reaction to some of my draconian treatments.

If any of you have had luck with something let me know! In the meantime I’m trying a few treatments. As much as I try to avoid chemical nastiness in the garden, I’m desperate. I’m removing the galls and swabbing the infected area with a 50% bleach solution. I’ve applied the systemic insecticide imidacloprid at the roots, hoping that the insecticide won’t affect the beneficial bugs feeding on the plants nearby. Then I tried to spray just the affected plant–a big 12-16 footer–as best as I could with Bayer 3-in-1, which in addition to imidacloprid contains the miticide tau-fluvalinate. I don’t know that these treatments will do anything other than relieve me of guilt that I didn’t try what I could to save the plant.

Wish me luck.

12 thoughts on “exotic plant, exotic pest”

  1. I’m sorry for your aloe trouble. We in Austin are facing a scourge of agave weevils taking out our biggest agaves. It’s heartbreaking to lose a plant like that.

  2. Oh, it can be so frustrating to deal with a pest that has no proven way to eradicate it. Your tree aloes are so majestic and it hurts me to see them suffer. I wish I had some advice, but I do not…just know that I empathize 🙂

  3. I wonder if climate change is bringing on all manner of new phenomena and we are just beginning to see the tip of the ice (melting) berg. Sorry, that was the opposite of helpful,wasn’t it? I do wish you well in your campaign to save your fabulous tree, but more I cannot offer.

  4. Pam, thanks for the concern. I know you have some special agaves, and hopefully they don’t attract the attention of the weevils.

    Loree, thanks for the recommendation. I’ll see if they have any ideas.

    Noelle, I appreciate the commiseration! Even our native plants are going through various blights–borers in our oaks, for example.

    Ryan, that’s my main worry right now. The two plants touch in a spot and I’m watching that area closely. And then there’s another huge mound of aloe only 3 more feet away. I hope I don’t lose the dramatic structure of the garden with the loss of three plants of this genus.

    Candy, thank you. I’m keeping my fingers crossed too.

    Ricki, there’s a lot of truth in what you say. This particular mite supposedly is limited by cold weather, but it’s been many years since we dipped below freezing longer than to put a light glaze on the car windows.

  5. I wish you much luck. It is awful to sit back and feel helpless when one of your prized plants is dying. Let us know how it goes. Good lcuk!

  6. Oh no, how heartbreaking. I find that when plants are afflicted by a pest, it’s usually because there were other stressors involved that drew the mites to the plant in the first place. It’s rare to see a healthy plant completely taken down by one attacker, so maybe it was affected by less water from the neighbor’s lawn, etc? Sorry, that’s not really comforting, but at least you know that you’ve done everything you possibly could, including going against your organic preferences (which I think really shows you care!)

  7. Hello,
    I have recently fallen for the majestic beauty of the cacti/succulent world. I planted a 12ft Barberae less than a couple of months ago and cannot stand the thought of a virus affecting its health and beauty. It has been a year since this post. How are your plants doing?


  8. Daniel, the news isn’t good, and I’ll be doing a followup. The aloe mite was an issue, but I’m thinking that the worse problem in this case was gophers chewing on the aloe’s roots. The nearby smaller barberae looks just fine–no mites to speak of, while the larger one is just about gone. Good luck with yours!

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