Like any other plant, orange trees can be attacked by pests or fungi. With a little attention, small and large catastrophes can usually be avoided. A close weekly look under the leaves and on the branches often reveals in advance a newly established aphid colony or even a new scale insect population slowly migrating up the branches.
fungal diseases
In principle, fungi can colonize all parts of the plant, from the roots to the flowers and fruits, the entire orange tree is often affected. Mushrooms thrive particularly well in a warm, humid climate, which is why you should react in good time to any signs of suspicion, especially in the case of oranges, which love warmth and moisture. Fungal infestation occurs particularly frequently after overwintering too warm, e.g. B. in the warm living room, or after an infestation of scale insects.
Base rot leads to tree death
The so-called base rot is probably also caused by a fungus and usually begins at the lower end of the trunk. Initially, some parts of the bark turn dark, later flaking off. The tree exudes a gummy liquid on the affected areas. The disease is highly contagious and also spreads throughout the tree - including the roots, which is why the orange tree eventually dies.
The most common pests
In addition to fungi, numerous harmful insects also cause problems.
scale insects
These lice can be recognized by their small labels and are usually located on the underside of the leaves along the pathways and on the shoots. The larval form is very small (about 0.5 mm), white and very mobile. The sticky honey excretions, which are sprayed up to 15 centimeters wide by the animals, are often the first to be discovered. A sooty mold fungus likes to settle on these excretions, which covers the leaf black. The adult scale insects can be treated most gently with a mineral oil spray, the larvae with potash soap.
Aphids, mealybugs and mealybugs
An aphid infestation can be recognized from afar by the stunted shoots and twisted leaves. They prefer to stay on soft new shoots. Mealybugs and mealybugs are whitish to pink in color and up to four millimeters in size. When infested, they can multiply explosively. They sit on the undersides of leaves, in leaf axils and shoot tips. These lice are treated with the same means as other sucking insects, but several times in a row. This ensures that the juveniles that later hatch from the eggs are also fought.
Red citrus spider mite
This spider mite belongs to the arachnids that suck plant sap. The adult animals are almost 0.5 millimeters in size and red. An infestation can be recognized by light spots on the leaves. The animals usually sit on the undersides of the leaves. In the case of severe infestation, they also form webs there and in the leaf axils, which can spread to the entire shoot tip. Spider mites prefer dry air. An increase in humidity therefore reduces the infestation. Predatory mites can also limit an infestation, but they need temperatures around 20 °C. Spider mites can be combated with a mineral oil spray or potash soap if they occur more frequently.
tips and tricks
A lively ant activity in the trunk and root area is extremely suspicious. On the one hand, ants love the sugar excretions of the aphids and therefore take great care of these pests, on the other hand, they damage the roots of the plants with their own nursery in the root ball through their digging activities.