Aloe mite (c) Debra Lee Baldwin

How to Manage Aloe Mite

They seem everywhere this spring: mite-damaged aloes ranging from dwarf cultivars to tree 'Hercules'. The microscopic pests (Eriophyes aloines) are not insects but spider relatives. They cause deformed flowers, a bubbly fringe on leaf edges, and orange-and-green growths where leaves meet stems.

Aloe mite

Aloe mite causes distorted, cancerous-like growth

Google "aloe mite treatment," "aloe mite prevention," "aloe gall" or "aloe cancer" and you'll discover that distinguished experts, landscape designers, succulent societies and growers, and even federal agencies are aware of the problem. Yet they don't agree on what to do about it. Environmentally-unfriendly chemicals supposedly help to some extent, but are expensive, come with cautions, and aren't allowed in certain states (like California).

Mites, protected within galls, are impervious to topical pesticides. To protect rare and valuable specimens, aloe growers and collectors may apply a preventive systemic---a miticide that's taken up into the tissues of the plant via the roots---but it has to be applied before there's evidence that it's needed.

Aloe mite (c) Debra Lee Baldwin

Aloe mite on dwarf aloe

Here's what to do: At first sign, excise affected tissues and bag them for the trash (do not put them in green waste). If an infestation is severe, dispose of the entire plant. After all, it's a breeding ground. Even if you don't mind the galls, do get rid of them before the pests inside them find your neighbors' aloes...or mine. [Update: See expert Duke Benadom's comment below.]

Mites inject a chemical that causes cancerous growth. They produce as many as eight generations a year, and each female lays 80 eggs a month. Mites travel via water, wind, garden tools, and people who find bizarre formations fascinating.

It's not the end of the world. These photos, taken in my own garden, show two different aloes six weeks after gall-removal surgery. I simply used a sharp knife to slice the plants well below any signs of infestation.

Aloe nobilis (c) Debra Lee Baldwin

Aloe nobilis, new growth

Aloe rupestris (c) Debra Lee Baldwin

Aloe rupestris, new growth after gall removal

Other Pests and Problems

Lush green growth after winter rains means that insects of every kind---indeed, the entire food chain---are proliferating. Find out "What's Wrong with My Succulent?" and what to do about it on my website, my YouTube channel, pages 76-77 of Succulents Simplified and 137-142 of Designing with Succulents.

 

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10 Comments

  1. debraleebaldwi on March 30, 2019 at 2:56 pm

    Via email from succulent expert and author Duke Benadom of the Los Angeles Cactus & Succulent Society: “I completely agree with your comments on systemics; however, the product Sevin (liquid form) works excellently as a topical spray. It’s what is used in botanical gardens in Africa, and it works wonders here too. Cutting away the gall will remove a great nimiety of mites, but as one could imagine, countless others remain elsewhere on the plants. Not only do we never cut off the gall (unless it’s just part of the inflorescence), we leave it on the rare, non offsetting varieties until it gets rather large, and then we apply Sevin two or three times over a period of two or three weeks. The gall then grows into several new stems; this is a great propagation method for the rare stuff. This, of course, cannot be done by removing the gall.

    I should mention that I have seen evidence of Sevin in powder form damaging tissue, but the liquid form works wonders. Since discovering that curing large masses of gall with Sevin produces numerous offsets, I have shared this advice with many others who have in turn tried it themselves. It’s become known as one of the best ways to induce offsets.

    Re alcohol: It really does work, but one must hit every mite to get rid of them as there is no residual effect. The alcohol is believed to smother the mites. Spraying Sevin, only on the effected areas, a week or so apart seems to kill all mite activity (as does systemic miticide) and I’ve seen no adverse effects on adjacent flora or fauna.

    Myself and a plethora of Aloe enthusiasts are in agreement that most foliar applications are fruitless, but Sevin really works. I’ll have to look again, but I doubt that Sevin, Inc. really knows how well their product works in this regard.

  2. Roz Tampone on March 31, 2019 at 10:20 am

    Hi Debra,

    I enjoyed reading your article on aloe mites. In January, I noticed an unusual growth on an aloe in a container. I confirmed with members of the Fresno Cactus and Succulent Society that it was aloe mite. The only way for me to see the mite was under a microscope.

    Attached are a few photos.

    Best regards

    Fresno Roz
    Roz Tampone
    Fresno County Master Gardener

  3. Rita on April 5, 2019 at 12:42 pm

    What exactly is a gall? How would I recognize it?

    • debraleebaldwi on April 5, 2019 at 1:00 pm

      Hi Rita — An aloe mite gall is a knobby, cancerous-like growth that often has orange streaks or edges, may look bubbly, and is most often seen where leaves meet stems but also appears on leaf margins and flower stalks (which it distorts).

  4. Glenn Mejia on April 5, 2019 at 2:05 pm

    I’ve had good success with cutting the gall off of a large unidentified single-stemmed aloe. After cutting, however, I brushed a bit of formaldehyde directly on the excised area. I repeated this for 5-6 weeks until the gall stopped appearing.

    I don’t know if using the procedure Mr. Benadom referred to would’ve worked on my aloe but even I had known about it, I think I’d still rather get rid of the gall before it got out of hand.

    • debraleebaldwi on April 6, 2019 at 12:03 pm

      Hi Glenn — I know, I thought of that too…if the gall remains, it’s unsightly. Yet Duke sent me a photo showing that healthy new growth forms at the gall site. In fact, can provide cuttings if you want to reproduce the plant.

  5. Sally Bennett on June 7, 2019 at 7:24 pm

    Can you use seven dust instead of the liquid form?

    • Debra Lee Baldwin on July 7, 2019 at 11:37 am

      Hi Sally — I checked with Duke Benadom, who replied:

      “I know of at least one person who used dust instead of liquid, and it killed some aloes. Not recommended. Unfortunately, I just learned that the primary chemical used in liquid Sevin has been replaced with something new. I do not know if the new stuff will work the same, but I doubt it. It would seem that if a company changed a primary ingredient, they should also change the trade name.”

  6. Debra Lee Baldwin on July 7, 2019 at 11:30 am

    Leslie Kelly of South Africa writes: “I have been using Spirotetramat very successfully for 2 years in conjunction with other insecticides to control aloe mite.” She emailed a link to a scientific and academic study of it: https://academic.oup.com/jee/article-pdf/107/6/2088/21940998/jee107-2088.pdf.

    Duke Benadom notes: “The chemicals used in various countries in Africa have little to no control because of little to no testing for effects on humans, and while probably effective, they are not available here, nor are they tested for carcinogens here.”

  7. Frank Samson-b on August 15, 2019 at 11:42 pm

    Hi!! I just came across your great article today (in mid-August 2019).

    FYI… To my knowledge, the Sevin trade name was purchased by GardenTech a few years back and in 2018 they started phasing out carbaryl as the active ingredient in Sevin and replacing it with zeta-cypermethrin, a newer pyrethroid. Just thought it might be beneficial to know what the active ingredient was in the Sevin that was used (as mentioned in Duke Benadom’s recommendation).

    Thank you, Miss Debra, for your countless contributions to the understanding of and the fascination with succulent plants!!

    With all due respect and appreciation,

    Frank

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