It is completely normal for fungi to live in the soil and on plants and occurs everywhere in nature. Houseplants are not alone in their pots either. In addition to the roots of the plant, there are also innumerable microorganisms and fungi in the earth. Under certain circumstances, however, these fungi can spread widely and pose a threat to the plant.

Saprophilic mushrooms

Of course, fungi also occur in the flower pots of our indoor and container plants and in most cases are completely harmless. These so-called saprophilic fungi are mainly found on dying plant material. There they contribute to a well-functioning ecosystem. In the soil, on dying plants and also on the compost, this mold decomposes the organic material so that the nutrients are available again for other organisms. These mushrooms mainly include the following genera:

  • Alternaria
  • Penicillium
  • Aspergillus

Powdery mildew and gray mold

Regardless of whether it is powdery mildew or downy mildew or gray mold, these fungi are extremely rare in indoor plants. They mainly attack palm trees that are cultivated outdoors in summer or all year round. The white coating, by which the harmful fungi can be recognized, is mainly visible on the leaves, in the case of downy mildew, mainly on the underside of the leaves. Powdery mildew and gray mold (gray rot) are able to spread through flying spores and need a lot of sunlight.


The most common causes of proliferation of fungi include care errors and unfavorable weather conditions. If the plant is severely weakened, it offers excellent conditions for pests and diseases.

  • humid, cool climate
  • too wet root ball (root rot)
  • large wounds with wind breakage and cut
  • evenly high temperatures (especially in winter quarters)
  • poor ventilation
  • fallen leaves on the ground

But not only fungi can cause a whitish coating on the leaves and parts of plants. Another possibility for a floury or woolly topping is mealybugs, which, however, are easy to identify on closer inspection. Gall mites, which in this case do not form galls and are therefore very difficult to distinguish from molds, are particularly common in yucca palms


For example, mold can enter the plant through putrefactive, dead roots. The fungus then spreads further in the palm. Sometimes a white mold coating appears on the leaves of the palm tree first. In this case, it is often powdery mildew or gray mold that has been transmitted to the plant through the air.

1. Remove mold

Now it only helps to get rid of the mold as quickly as possible in order to save the plant and avoid health problems for the residents. Therefore, if possible, cut off the most severely affected parts of the plant and wash the remaining shoots and leaves under running water or with a damp cloth.

2. Repot

Use a new pot for repotting. If this is not possible, wash the old container with hot water with a dash of vinegar or alcohol to kill any germs it may contain. High-quality palm or potted plant soil is recommended for topping up.

  • Remove as much potting soil as possible
  • Cut away dead roots
  • use a clean, sterile container
  • only use suitable, high-quality plant substrate
  • ensure good drainage
  • Create a drainage layer made of perlite, lava granulate or expanded clay

3. Powdery mildew

Powdery mildew is very difficult to control. In the case of a slight infestation, a spray mixture made from field horsetail or onions can help.

  • about 400 g fresh onions or field horsetail
  • 2.5 liters of water
  • Soak in water for 24 hours
  • then cook for 30 minutes
  • sieve
  • Spray several days in a row
Tip : In stubborn cases, only a sulfur-based pesticide can help against powdery mildew.

4. Suckling insects

Gall mites and mealybugs can be effectively removed from palm trees with a mixture of detergent and water. Mix a few drops of surfactant with lukewarm water and wipe the leaves of the infested palm with it for several days in a row. Do not forget the underside of the leaves during treatment!


If you want to prevent infection, houseplants should be repotted regularly in the spring. Also make sure that it is in a perfect location and under ideal care conditions.

Air circulation

Provide adequate ventilation for indoor plants without exposing the palm to cold drafts. Outdoor plants must be protected against frost, but good air circulation is also important here so that mold does not develop.

Avoid waterlogging

In order to avoid waterlogging – one of the most common causes for the spread of mold – it is important to water the plant properly. Depending on the type of palm and the prevailing temperatures, the plant needs more or less water. It is important that the root ball can always dry well before watering again, because this is the only way to deprive the fungus of its livelihood.

Optimal location

If the palm tree is outside on the balcony or terrace in the summer months, it should be taken indoors during periods of persistent rain or very high humidity to prevent mold. In any case, it is necessary to place them in a sheltered and airy location so that the soil and leaves do not get permanently wet.

In the event of a strong mold infestation or sucking insects, the palm tree can often no longer be saved. It is therefore important to prevent disease in advance through suitable pouring behavior and an optimal location. With regular checks and early detection, quick action can save the palm in most cases.

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