With good care and a suitable location, lice and other pests have a hard time, because the yucca (and of course other indoor plants) then have enough defenses. However, weakened plants cannot defend themselves and are therefore defenseless against an infestation. So if you notice pathological changes, especially on the leaves of the yucca, you should react quickly and appropriately.
If the leaves stick, it is a lice infestation
First indications of a pest infestation and its causes
In many cases, a pest infestation on the yucca can only be recognized by sticky leaves or leaf discoloration or deformation. If the tree "sticks", it is very likely plant lice, often scale insects. A white, floury coating, on the other hand, can be an indication of powdery mildew (which is rare in yucca), but also of gall mites. Brown spots or similar, on the other hand, are due to fungi, but often also to damage caused by leaf sap-sucking pests such as spider mites. Plants are usually only attacked by incorrect care or plants that are too dark or too dry.
Common pests - and how to fight them
Check the yucca regularly for animal pests. Many like to sit on the tips of the shoots, young leaves, but also on the undersides of the leaves and the leaf axils. You are also welcome to use a magnifying glass.
plant lice
Plant lice include aphids, scale insects and mealybugs. These little creatures are often noticed by a sticky coating on the leaves. These are the excretions known as “honeydew”. All lice can be treated well with a spray treatment, for which you mix 10 drops of tea tree oil (or lavender oil for aphids) with a liter of warm water.
gall mites
An infestation with gall mites on the yucca can easily be confused with powdery mildew, which is shown by a white and mealy coating. Unlike other plants, this mite does not form galls on the yucca, which is why it is easier to control here. Spraying with dishwater helps in many cases.
Spider Mites (Red Spider)
If there are small bright spots on the upper side of the leaf and perhaps a fine web on the yucca underneath, then it is spider mites. These only occur when the air in the room is too dry, which is why increasing the humidity (or putting the affected plant outside) can help. Mist the plant with a tea tree oil-based solution, although you can resort to neem supplements for stubborn cases.
tips
Pests can also be brought into the house through already infested, newly purchased plants. Since an infestation is not always obvious at first glance, it is best to quarantine the newcomers in a cooler, not directly sunny place. Bring them to their final location only after a few days.