A healthy single leaf has dark green, glossy leaves. If the plant is not doing well, you can tell by a discoloration of the foliage, among other things. Brown spots or dots are often an indication that you meant too well with the fertilizing. But a pest infestation and the quite common leaf spot disease can also be behind this phenomenon.
Brown spots on the single leaf can have various causes
Note on over-fertilization
Depending on the size of the plant, the location and the season, the single leaf is supplied with a houseplant fertilizer about every two to eight weeks. Over-fertilization, i.e. an excessive supply of nutrients, is noticeable over time as brown spots on the leaves. In such a case, repot the plant in fresh substrate and reduce the amount of fertilizer.
pest infestation
Especially if the plant is too dry or the humidity is too low, the single leaf will initially get brown leaf tips. In addition, the weakened plant can later be attacked by pests such as spider mites or the red spider. They love dry, warm air and feed on the nutritious leaf sap. By piercing the veins of the leaves, small brown dots are formed. Later, the whole leaf discolors and eventually dies.
How to get rid of spider mites & co
Spider mites & Co. do not like high humidity, which is why you can both prevent and fight an infestation by spraying the plant regularly. However, only use decalcified water or soft rainwater, which should also be warmed to room temperature.
leaf spot disease
If the spots on the leaves are dark brown with a lighter edge or light, ring-shaped and crumbly - both variants are possible - then there is a high probability of leaf spot disease. Typically, the lower leaves in particular also dry up. To combat the disease, you must remove the affected leaves and dispose of them with household waste. In severe cases, special preparations from specialist shops help, whereby you should primarily rely on organic quality - all other agents should not be used in living areas.
tips
In order for your single leaf to feel comfortable, ensure a suitable location, fertilize the plant regularly and keep both the air and the substrate evenly moist. However, avoid waterlogging.