Gall mites are often found behind a white coating
In the case of the yucca, powdery mildew, a fungus that is otherwise not uncommon in many plants cultivated in the home and garden, is rarely the cause of a floury-white coating that can be wiped off. If you discover this damage on your yucca, you should first think of gall mites - tiny little animals that cannot be seen with the naked eye. Pesticides based on sulfur or rapeseed oil help against gall mites - just as they do against powdery mildew.
also read
- White toppings on the yucca palm are not just powdery mildew
- Yucca Palm Fungal Infection - And What To Do About It
- Powdery mildew on yucca is very rare
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 with their sweet excretions, and the soil around the affected plant can also stick. The stubborn little animals are best combated with tea tree oil: Mix 10 drops of tea tree oil with one liter of water and wash the leaves with it regularly. In the case of a strong infestation, however, the only thing that helps is to remove the relevant leaves and dispose of them with household waste.
Powdery mildew is rather rare on yucca
Powdery mildew (not to be confused with downy mildew, whose whitish coating cannot be wiped off) is rare on a yucca, but 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 summer. Remove the infected leaves and spray the plant with horsetail tea or a tea tree oil-water mixture.
Tips
Downy mildew also shows itself as a white coating, but only develops in locations that are too moist and too cool. Here, too, horsetail or tansy tea and the generous removal of infected parts helps.
