You can usually recognize fungal diseases by coatings on the leaves or sometimes shoots, by cotton-like coatings, partial wilting or by leaf spots and/or pustules.
Fungal diseases often show up initially as leaf spots
The most common fungal diseases in yucca palms
There are numerous fungicidal pathogens, but you can prevent an infestation by taking the following measures:
- Take care of the yucca in a species-appropriate manner. Above all, keep them dry rather than too moist.
- Make sure the yucca gets enough light.
- In summer, the yucca feels very comfortable outside - for example on the balcony.
- In winter it needs a rest phase at around 10 °C. Water little and do not fertilize.
- Don't overdo it with fertilizing!
- Strengthen your plants with horsetail or tansy tea, for example.
Fungal diseases are usually caused by care errors, which is why species-appropriate care is considered the best prevention. If your yucca does show signs, the following fungal diseases are among the most common.
root rot
Root rot is always due to substrate that is too wet, as a result of which fungi settle on the roots and decompose them. An infestation is present when you notice muddy and rotten spots on the roots, on the root neck and in the lower trunk area. Since the plants can no longer be properly cared for, they wither. Infested yuccas can be saved by cutting off and rerooting healthy parts of the plant.
stem rot
If the stem becomes soft and/or hollow, then root rot has already spread to the above-ground parts of the plant. In addition to the rotten roots and soft trunk, brown to blackish, often sunken and rotten spots appear on the leaves and shoots. This is a sign that the fungal pathogens are spreading and the yucca is dying. Partial rescue is possible, see root rot.
wilt disease
If the yucca suddenly and without reason drops its leaves and wilts, then in rare cases the dreaded wilt disease can be behind it. Since the roots appear to be healthy, excessive moisture is not the culprit in this case. Instead, the causative fungus comes from the infected soil, penetrates from there into the pathways and clogs them. As a preventive measure, only use germ-free soil and remove infested plant parts immediately and generously.
sooty mold
If a blackish coating appears on the leaves of the yucca, it is most likely a sooty mold fungus. This is always accompanied by an infestation by aphids or other plant lice, as it settles on their excretions called honeydew. Wipe off the honeydew and fungus with a damp cloth and fight the pests.
leaf spot
Various fungi cause round spots on the leaves, which often appear as rings of varying color and are often surrounded by a yellowish halo. These spots gradually enlarge and can sometimes spread over the entire leaf. The causative fungi are mainly spread by drafts or improper watering - for example by moistening the leaves. Do not wet the yucca leaves when watering and avoid drafts. Affected leaves should always be removed.
tips
A white coating on the leaves of the yucca can be an indication of an infection with powdery mildew - or an infestation with gall mites, which cause a very similar damage.