If you notice white spots on yucca leaves, it can be disheartening, but it’s usually something that you can fix relatively quickly.
In my experience of over five years of yucca ownership, white spots on yucca leaves are most commonly caused by excess humidity, pests, or fungal diseases like powdery mildew.
In this article, I’ll take you through the most common reasons for white spots on yucca leaves and what you can do to keep your yucca healthy.
Let’s get into it.
Should You Be Worried If Your Yucca Has White Spots?
Before I explain the most common causes of white spots on yucca leaves, it’s important to know whether it is something to worry about.
If you only notice a few leaves with white spots, you should be able to solve the issue very quickly. If all of the leaves have white spots, then there is a good chance that your yucca will die unless you treat it quickly and effectively.
It all depends on what is causing the white spots in the first place, so let’s take a look at the five most common reasons for them.
5 Causes Of White Spots On Yucca Leaves (& What To Do)
1. Powdery Mildew
Powdery mildew is a fungal disease that affects many plants, including yuccas, and is caused by a fungus that thrives in humid and warm conditions with poor circulation.
The disease first appears as small, white spots on the upper surfaces of leaves, which then grow and merge to form a white, powdery coating. Powdery mildew is super easy to identify as it looks exactly like you would imagine white powder scattered on the leaves to look like.
If you can spot signs of powdery mildew early on, it’s not going to be fatal for your yucca. You’ll need to remove any affected leaves and ideally move your yucca to a different location with better airflow and, ideally, less humidity.
The rest of the plant will need to be treated with either a commercial fungicide product or a homemade remedy, although I’ve found much more success with commercial options. Homemade remedies usually involve a mixture of water, baking soda, and dish soap.
Humid environments can be breeding grounds for fungus, especially if you mist your yucca and the airflow around the plant is not very good.
Water droplets can also leave behind white residue after they evaporate, which is very common if you mist your yucca.
If fungus has started to grow, remove any affected leaves and treat the rest of the plant with a fungicide.
You’ll also need to move your yucca to a drier location and stop misting it if this is something you have been doing. If your yucca needs water, then water the soil – misting is not an effective way of providing water or raising the humidity.
Pests can not only cause white spots on yucca leaves, but some even look like white spots themselves:
- Mealybugs – Mealybugs themselves are white and cottony and often mistaken for white spots on the leaves of yuccas. They feed on the sap in the leaves and excrete honeydew and wax, which can lead to sooty mold.
- Whiteflies – Whiteflies are closely related to mealybugs and are soft-bodied, white winged insects that, again, are often mistaken for white spots. These also feed on sap and leave behind honeydew, again causing sooty mold.
- Spider Mites – Spider mites are tiny (around 1/20 inch for females) and leave behind tiny white spots after feeding. Large infestations can leave behind webbing as well, which can look like white spots or patches on the leaves of yuccas.
The first step for dealing with pests is to wash down your yucca with water. This will remove the majority of the pests and can, in some cases, deal with small infestations in one go.
After washing, prune any leaves that have become damaged and then treat the rest of the leaves with an insecticide. You should also isolate your yucca from other plants if you haven’t already, as pests will quickly spread to other plants.
It’s also a good idea to isolate any new plants that you add to your collection for a week or two to make sure they don’t contain pests – you’d be surprised how often this can happen.
4. Nutrient Deficiency
Nutrient deficiency, particularly nutrients like phosphorus and potassium, can cause white spots to develop on yucca leaves.
This one is not as common as some of the others as yuccas are quite well-adapted to low-quality soil, but if you suspect that nutrient deficiency is at play, you have two options.
You can either repot your yucca in fresh potting soil, ideally mixed with compost to make sure it has a lot of nutrients, or you can simply fertilize the soil with a balanced fertilizer.
Yucca leaves can get sunburnt a lot easier than you would think, especially if they are kept inside.
Sunburn spots are usually brown in the center with yellow and brown halos, but the spots can also have shades of white as well. If your yucca has periods of direct sunlight each day and is starting to form random spots on the leaves, it is most likely due to sunburn.
This one is pretty simple, just prune any sunburnt leaves (or wait for them to fall off) and move your yucca to somewhere with indirect light rather than direct sunlight.
If your yucca is planted outside, it can take a while for it to adapt to direct sunlight, so it’s worth leaving it a few weeks, even if some leaves are getting burnt while it adapts.
Most of the time, your yucca will be just fine if it has white spots on its leaves.
If the majority of the leaves have white spots, then something has seriously gone wrong, and it’s either suffering from pests or some kind of fungal problem.
In the worst-case scenario, you can always try to grow cuttings that haven’t been affected yet, but most of the time, you should be able to get your yucca back to full health in a matter of weeks. Yuccas will live a long time if cared for properly, so don’t give up on yours just yet!