The end of the glorious winter bloom season for many aloes is near, but so may be the life of some of those lovely plants. Occasional instances of infection from the aloe mite (Aceria aloinis) have been noted for years, but it seems that the infestation may be spreading. More evidence of their damage has been noted of late.
Aloe mites are very small and may only be seen with the aid of a high-power hand lens or microscope. The damage they do, however, is quite disfiguring and very obvious. Like many insects that plague plants, they pierce the leaves or stalks and suck out the nutritious juice. In the process, they leave behind a chemical that induces the plant cells to proliferate abnormally. The chemical is a growth regulator and continues to affect the plant even after the mites are dead. While many call such structures galls, others have referred to them as cancers, which they resemble in formation and appearance. The resultant excess and deformed plant tissue surrounds the feeding mites and creates a safe haven for them and their future generations (up to eight generations per year, with each female capable of laying 80 eggs per month!). Since they seem to prefer tender new growth, the galls may appear most often in the center of the rosette of leaves or at the apex of the flower stalk.
There are no good solutions to ridding the plant of this pest except to cut out the affected part and discard it. Do not try to compost the trimmings; put them into the garbage and get them offsite. These mites are so small that they may be spread by the wind, so isolating them is essential. Another possible vector is ants, so if you observe ant activity on the affected plant, it would be wise to try and control their populations, as well. Early treatment will minimize the disfigurement of the aloe, but sometimes, a plant will be too affected and nothing short of digging it up and discarding it will serve. Keeping a lid on the aloe mite will ensure that aloes remain among the showiest flowering plants in our landscape.
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Virginia Hayes, curator of Ganna Walska Lotusland, will answer your gardening questions. Address them to Gardens, The Independent, 122 W. Figueroa St., S.B., CA 93101. Send email to firstname.lastname@example.org.