Q: I have attached a photo of my coral aloe (Aloe striata). After much searching, I believe the hideous, growth seen in the photo is aloe cancer/gall/mite? I have dug up, bagged and put the plant in the trash. Apparently, I can never have another aloe again except Blue Elf? Is this true, and is this wretched little mite a menace to my neighbor’s aloes? Is there anything else I should do? It makes me almost miss the killing freezes in Colorado!
A: I believe you are correct about the diagnosis. That appears to be damage caused by the eriophyid mite (Aceria aloinis). Because these mites are microscopic, it is difficult to know they are there until the damage is seen. There is some anecdotal evidence that the “Blue Elf” variety of aloe is unaffected but there is no science to back this up that I have seen. On the other hand, other known host plants include the aloe species arborescens, dichotoma, nobilis, and spinossima as well as Haworthia species. In general, I don’t see these mites as a widespread problem so I wouldn’t put all my aloe investments in one species. They are sporadic pests on aloes and based on the number of questions I get, many people don’t have a problem with them. These mites can spread by crawling and by wind. Because they can’t fly it isn’t a quickly spreading problem and your neighbor’s plants could very well be safe from infestation. What you did by bagging the infested plant and disposing of it is the best thing to do and probably enough to stop it from spreading.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to