Care errors
If the leaves of the lemon tree turn more and more yellow, it may be due to spider mites. However, if there is no pest infestation, you should assume a nutrient deficiency. There are various reasons for this:
- If roots are kept too moist for longer, root rot can be the cause, especially with bitter oranges as a refining base and cuttings. Due to the defective roots, nutrients are no longer transported into the crown and the leaves turn yellow.
- If the plant was kept too dry during the growing season, no nutrients can reach the crown, as no nutrients can be absorbed from dry soil.
- The plant has not yet been fertilized or has only been inadequately fertilized during the growing season. A sufficient supply of nitrogen is mainly responsible for the lush green leaves.
- Watering with lime-containing water also blocks the absorption of nutrients such as iron - especially with bitter lemon rootstocks. However, intensive iron fertilization is not recommended, as this in turn often creates rubber flow at the base of the trunk, which can cause the plant to die. In this case it is better to switch to lime-free irrigation water immediately.
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Damage due to incorrect winter storage
If your lemon tree loses many or even almost all of its leaves, this is usually due to a winter that is too warm and / or too dark. Another reason could be that the plant was once kept too dry so that the leaves have already arched upwards at the outer edge. Often all the leaves are thrown off after abundant watering. If the drought damage was not too great, the lemon tree usually sprouts again.
Pest infestation
Lemons are very often attacked by scale insects, aphids, mealybugs and mealybugs as well as spider mites. Sticky leaves and shoots always indicate an infestation with plant lice.
Scale insects
The tiny scale insects are difficult to see with the naked eye. They sit on the undersides of the leaves along the ducts and on young shoots. Due to the sticky honeydew excretion, the lemon seems to stick, and the liquid attracts ants. In addition, the sooty fungus, which coats the leaves black, likes to settle on the honeydew.
Aphids
Aphid infestation can be recognized from a distance by the stunted shoots and twisted leaves. The animals prefer to stay on soft new shoots.
Mealybugs and mealybugs
The white to pink mealybugs and mealybugs are usually found on the undersides of the leaves, in the leaf axils and in the shoot tips. They are about twice the size of scale insects, making them easier to spot.
Spider mites
Like plant lice, spider mites are also sap-sucking pests. An infestation can be recognized by light spots on the underside of the leaf; if the infestation is severe, webs form there and in the leaf axils. Spider mites can usually be kept in check by high humidity.
Tips & Tricks
You can counteract a pest infestation by soaking the lemon tree upside down in soapy water and leaving it for some time. However, the substrate must not get any soap, and the treatment must be repeated several times.
