Like any other (house) plant, the popular yucca - which is often mistakenly sold under the term yucca "palm" - is occasionally plagued by pests. Not only spider mites and various plant lice can be found, so-called gall mites also find palm lilies very attractive. An infestation with these tiny pests is difficult to recognize because the animals do not form galls on yuccas.
Chemical pesticides are not recommended
Identify gall mites
Instead, the damage is very similar to mildew infestation. Leaves and shoots are covered with a whitish layer, so that some plant lovers first think of a fungal disease and take appropriate countermeasures - which of course do not work, after all they are pests. Gall mites are tiny and can be found on a wide variety of plants, especially woody plants. The formation of the so-called galls is typical, but they are completely absent on yuccas.
Successfully combat gall mites
Gall mite infestation leads to deformation and leaf discoloration of the affected plant, with the damage mostly being of a visual nature and having little adverse effect on the host plant - unless a fungus joins in as a result of the mite infestation. These find welcome entry points in the numerous tiny punctures in the leaves of the yucca. Provided they are detected in good time, gall mites can be combated very effectively with plant protection products based on rapeseed oil or sulphur. However, it is important to act quickly so that the damage does not become too great. If you want to be on the safe side: Sulfur-containing plant protection products usually also help against powdery mildew.
Often only a radical pruning helps
Gall mites are difficult to spot and have often left severe damage to yucca leaves. These look unattractive, but once infested they will not regenerate. In such a case, only a pruning helps, even if it has to be radical. Fortunately, yuccas usually tolerate such a measure very well and will sprout again even if you have only left part of the trunk.
tips
If you want to cut back the affected yucca, apply tree resin to larger cut areas. Smaller ones, on the other hand, can be sprinkled with cinnamon or charcoal powder and thus disinfected.