If the yucca or palm lily is treated with care, diseases or pests are very rare. If the popular houseplant is placed in a bright and warm place - if possible directly in front of a window - is not watered too often and fertilized occasionally, it will grow quickly and develop strong, green leaves. A white, wipeable coating is often due to gall mites, but plant lice or mildew can also be a possible cause.
What causes a white coating on the yucca palm?
A white coating on the yucca palm can be caused by gall mites, plant lice or powdery mildew. Plant protection products based on sulfur or rapeseed oil, tea tree oil or horsetail tea can be used to combat it. Affected leaves should be removed.
Gall mites are often hidden behind white deposits
In the case of the yucca, the cause of a floury-white and wipeable coating is rarely powdery mildew, a fungus that is otherwise not uncommon in many plants cultivated in the home and garden. If you discover this damage on your yucca, the first thing you should think about is gall mites - tiny little animals that cannot be seen with the naked eye. Plant protection products based on sulfur (€8.00 on Amazon) or rapeseed oil help against gall mites - just as they do against powdery mildew.
mealybugs and mealybugs
However, a white coating is not only due to gall mites, but sometimes also to plant lice such as mealybugs or mealybugs. In contrast to gall mites, lice cause sticky leaves through their sweet excreta, and the soil around the affected plant can also stick. The best way to combat the stubborn creatures is with tea tree oil: Mix 10 drops of tea tree oil with a liter of water and wash the leaves regularly with it. In the case of a severe infestation, however, the only solution is to remove the relevant leaves and dispose of them with household waste.
Powdery mildew is rare on Yucca
While powdery mildew (not to be confused with downy mildew, whose whitish coating cannot be wiped off) is rare on a yucca, it does occur occasionally. The cause is a location that is too dry and/or too warm, which is why you should never place the yucca directly next to a heater during the winter months and it is best to place it outside in the summer. Remove infected leaves and spray the plant with horsetail tea ora tea tree oil and water mixture.
Tip
Downy mildew also appears as a white coating, but only develops in locations that are too moist and too cool. Horsetail or tansy tea also helps here, as does the generous removal of affected parts.
