The most common diseases of rhododendrons are browning of the edges and tips of the leaves. One of the main reasons for the appearance of this type of symptoms are unfavorable conditions during autumn and early spring, e.g. drafts, cold winds, temperature fluctuations.To prevent this type of symptoms, we protect plants against cold, using various types of mats or nonwovens.
Weakened tissue is often infected by fungi belonging to many types, which we fight with using fungicides intended for a given disease.Symptoms of iron deficiency can be seen very often on rhododendron leaves. Light green, yellowish discoloration appears on young leaves between the veins. Prevention of iron deficiency involves spraying the plants with iron chelate or iron-containing fertilizers.
Diseases of rhododendron leaves caused by fungi are anthracnose, leaf spot, powdery mildew and bedding. Anthracnose is caused by the fungus Colletotrichum gloeosporioides.Small, oval, grayish-brown spots appear on the leaves.As the disease progresses, the spots grow larger and you can see rings on their surface. Infected leaves die.
Leaf spot caused by the fungus Cercospora Handelii is characterized by similar symptoms.We fight it like anthracnose.Powdery mildew Microsphaera penicillata may also appear on rhododendron leaves.
In this case, we notice a white powdery coating of mycelium on the leaves, which over time covers the entire leaf blade, leading to deformation and dieback of the leaves. Against them, we use fungicides that match the disease.The leaves of rhododendron and other heather plants also feature Exobasidium vaccini azalea, forming growths on the lower side of the leaf plate.
Rhododendrons and azaleas
At first they are white, then pale pink and reddish.Affected leaves turn darker, then turn yellow and die, and the growths harden.The fungus hibernates in fallen prematurely infected leaves. Remove the leaves with symptoms. Then spray the bush with a fungicide. The fungus also hibernates on infected shoots, which should be cut after finding symptoms.
