Yucca palms are among the low-maintenance plants that only need the right location and a permeable substrate to thrive. But even palm lilies can suffer from a variety of diseases that sap the vitality of the plants and, if not treated, lead to the death of the plant. Most of these diseases are due to care errors, which makes countermeasures easier to apply.
Dead leaf tips
Dead leaf tips are dried up and a light white color. They announce themselves by becoming lighter over time, but no spots appear that would indicate other diseases. This disease is not an infection and is not caused by moisture, which is the main cause of many problems with the drought tolerant yucca. The reason for this is a too low PH value of the substrate, causing:
- Plant is under stress as cells die
- the tips of the leaves die off
- in addition, the tips of the leaves turn light, almost white
The desired pH value of the yucca is between 6.0 and 7.0, which shouldn't even be a problem with the calcareous water in Germany. If dead leaf tips appear, check the soil pH and adjust accordingly:
- 150 grams of calcium carbonate per square meter to carefully increase the pH value
- Ten grams of basalt flour per liter of substrate to increase the pH value by one unit
You do not have to remove the dead leaf tips as long as no other disease has attacked the yucca.
leaf discolouration
Discoloration of the leaves is one of the typical diseases caused by incorrect care. These are not an infection or a pathogen, you just need to take proper care of the plant. The typical leaf discolorations are either yellow or brown and are caused by the following care mistakes:
- too frequent watering without waterlogging: the entire leaf discolours
- Lack of light on one side: one side of the leaf discolours
Act on the cause. You can leave the leaves on the yucca without any problems, because they will fall off by themselves.
stains
Stains on yucca can be caused by a variety of mushrooms are caused and affect the health of the plant accordingly. These are transmitted either via drops that get onto the leaves or spores that are transmitted by drafts. Since a yucca should never be watered from above and should not stand in a draft, these diseases can be prevented with the right location and watering. However, infection can always occur, with the following spot colors indicating disease:
1. Gray
Gray discolouration is caused by spores of the genus Cytospora and occurs mostly in the gray yucca (bot. Yucca aloifolia). First, the tips and edges of the leaves die off, turn gray, and then gray spots appear. This is due to using too warm water while watering too often.
2. Rust colored
If rust-colored spots appear, fungi of the genus Cercospora are to blame. These turn brown over time and indicate the infection. Over time, the spots grow to a size of over 60 millimeters and are clearly visible. It is best to only water from below.
3. Brown and yellow
These discolorations are caused by the fungus Coniothyrium concentricum, which produces brown and yellow spots that are outlined in black. The older leaves of the plant are particularly affected and the discoloration spreads so much that the entire leaf dies off. Casting errors are also to be avoided here.
countermeasures
For all these diseases, proceed in the same way:
- keep infected plants away from other specimens
- Cut off infected plant material and dispose of with household waste
- Treat lightly infested plants with natural fungicides
- for example infusions based on nettles, horsetail and tansy
- if the infection is more severe, chemical fungicides must be used
- fungicides based on copper and sulfur are recommended
- Broadband agents also work
- never use fungicides indoors!
tip: Discoloration can often occur via pests, which requires a completely different approach. Therefore, check whether the stains are caused by a pest infestation.
mildew
Powdery mildew is a fungal infection that mainly affects the leaves of the plant and is quite rare. The most common reason for powdery mildew infection is either transmission from other plants suffering from the fungus, or poor care. Typical causes of infection are:
- incorrect, usually too frequent, watering
- incorrect fertilizer additions
- lack of light
- wrong temperature
- Heating air, which greatly dries out the area around the plant
The pillar fungus Athelia rolfsii, which mainly chooses tomatoes and soybeans as host plants, is responsible for the powdery mildew. However, it can affect the yucca and can then be recognized as a white coating on the leaves, which can be wiped away by hand. In the case of a mild infestation, the leaves are treated with a mixture of whole milk and water, as the lactic acid bacteria contained reliably kill the fungi. If there is a severe infestation, you must remove the affected leaves and areas and dispose of them in the household waste. Then check whether there is a possible maintenance error. After cutting, don't forget to disinfect the scissors.
tip: A disease similar to powdery mildew can be caused by an infestation with gall mites. As soon as you inspect the leaves and it is not a wipeable plaque but small mites, you need to take action against gall mites.
root rot
Root rot is one of the most serious diseases of yucca, since these large damage can cause and also requires a lot of care so that it can be overcome. The trigger of root rot in the yucca is actually always involved waterlogging together. If the fleshy root ball is actually in the water, it begins to become soft and susceptible to fungi of the Fusarium genus, which lead to said root rot and mold. Likewise, various putrefactive bacteria can be the cause of this disease. But not only waterlogging is a breeding ground for the disease, because the following care mistakes also lead to:
- Compacted substrate due to insufficient repotting
- Injuries to the stem, for example from pruning or if the plant falls over
- Humidity over 85 percent
- permanent, lack of drainage without waterlogging
- planted too deep in the pot
- Yucca grows only weakly
- Roots are damaged during repotting or other causes
- Location in winter quarters too cool
- dirty cutting tools that can lead to infection
- rare infection by fungi or bacteria of an already infected plant
- when buying bacteria or fungi are introduced
symptoms
Despite these causes, waterlogging is the yucca's biggest problem. The plants originally come from arid and semi-arid areas of the world and can therefore tolerate longer periods of drought without any problems. Numerous diseases such as root rot can be avoided by not watering too often, especially over the winter. The disease is most common at this time of year because many owners avoid watering the yucca less. Root rot is also known as stem rot and is associated with a variety of symptoms.
- Mold formation on the trunk, in the substrate and on the substrate surface
- a musty smell can be heard from the earth
- trunk is soft; a particularly clear symptom of the disease
- stunted growth
- yellowing leaves
- rotten roots
countermeasures
To cut
Since there is no remedy against the fungi and bacteria responsible for root rot, only vigorous pruning measures remain. Although the palm lily loses a large part of its plant material through this, it can then sprout again. Proceed as follows:
1. Remove the plant completely from the pot and use disinfected scissors to remove any rotten roots. Rotten roots are soggy, brown, and smelly. If there are still healthy roots, the disease has not progressed too far, which is a good sign.
2. Also cut off any affected areas on the plant that are also soft. Yellow leaves are also included. Check the yucca closely for moldy areas and areas that are soft. So also cut back all shoots that are affected by the rot.
3. Then wash the root ball of the plant thoroughly and then dry it well.
4. Dispose of the old substrate with the household waste, wash the pot well and check whether it has drainage holes. Then fill it with fresh, well-drained substrate and plant the plant in the ground. After that, be careful not to water too much so that the disease does not reappear. Cut off parts are disposed of in the household waste, since these would lead to the formation of further fungi on the compost.
Draw a palm tree as a new specimen
If the root rot is very advanced and there is a lot of mold, you need to take another measure. Especially when the entire root area and parts of the trunk have rotted, the entire plant must be disposed of, as it can no longer survive and would only continue to be a breeding ground for fungi and bacteria. However, you do not have to dispose of the yucca, you can use the last remaining leftovers draw a new copy:
1. Take the plant out of the pot and completely remove the substrate again.
2. Cut back the plant until you reach solid wood. You need to be generous here, trimming away as much as possible so that there really aren't any soft or rotten spots. Even if you end up with only a small piece of the original plant left, this step is necessary.
3. Now plant the solid parts like cuttings in fresh substrate and grow new plants from them. Above all, pay attention to the right care and remember: do not water too much! You can even wait until the plant droops its leaves before watering. You can water as long as the leaves are not discolored and only droop slightly.
tip: Yuccas planted in the garden suffer less from root rot and diseases in general than the specimens in containers. The reason for this is the better drainage of the soil, which in most cases can prevent waterlogging.