When the leaves of the magnolia die off, pests or diseases are often to blame. We introduce you to the most important diseases and pests.
Diseases and pests rarely appear on magnolias. However, there are one or the other disease that affects the magnolia, or rather some pests that tamper with the magnolia from time to time.
The most important diseases and pests include e.g. leaf spot caused by Pseudomonas bacteria, powdery mildew, whitefly and scale insects.
These Diseases and Pests Affect Magnolias
Leaf spot disease
Bacterial leaf spot disease occurs with black spots, each surrounded by a yellow areola and bordered by their leaf veins. Over time, holes form within the center of the spots. In addition, affected shoots of the magnolia can die off.
Combat
Pseudomonas bacteria are mainly spread by raindrops and thrive mainly in humid conditions. Accordingly, the foliage of the magnolia tree must be able to dry quickly for treatment. An airy location and a loose crown, sufficient planting distance and no watering/watering from above are helpful here.
Whiteflies
Whiteflies are only about 1.5 millimeters in size, but the insect can still damage a magnolia. The whitefly deposits its approximately 0.5 millimeter long eggs on the underside of the leaves, from which the larvae hatch after some time. Nymphs and adults then feed on the leaf sap. The whitefly also releases honeydew. This promotes the growth of mold and other fungal diseases, so that leaves fall off and the fruits of other affected plants remain small.
Combat
Natural enemies such as the ladybug are a good way to combat whitefly effectively. If their use still doesn't help, you can resort to insecticides.
Mildew
Powdery mildew can be recognized by the typical whitish coating that is on the surface of the leaf and often also on the underside of the leaf. The clinical picture is caused by fungi thatof the Erysiphaceae family.
Combat
If you have a mildew infestation, you can try to reduce it with various preventive measures. This includes, for example, ensuring good lighting and making sure that the plants are not too close together. However, if this does not improve anything, you can also use an appropriate pesticide.
scale insects
Like whiteflies, scale insects suck plant sap and also excrete honeydew.
Combat
Even if you have a scale insect infestation, you can first try natural enemies such as ladybugs. Otherwise, a pesticide can help (see Insect Repellent for Plants).