Camellia Bush Problems
Camellias are slow-growing, long-living evergreen shrubs that produce showy winter-blooming blossoms. They vary in size and appearance, depending on the variety or cultivar, and are often used as shrub borders or specimen plants. Camellias grow best in nutrient-rich, well-drained soil and partial shade, and must be watered regularly. These plants are generally healthy, but insect pests and diseases occasionally cause problems for them. Environmental issues can also cause poor growth.
Stem and Root Diseases
Camellias are vulnerable to fungal infections that attack the stems and roots. For example, Phytophthora cinnamomi is a soil-borne fungus that causes root rot. It most often affects plants that grow in areas with warm temperatures and poor soil drainage. Infected camellia roots cannot transmit water to the rest of the plant. Diseased camellias may turn yellow and their branches sometimes wilt and die. Dieback or canker also affects camellias. The Glomerella cingulata fungus enters the plant through wounds such as insect bites or pruning injuries and creates sunken areas of bark on the stems, called cankers. The growth above the stem turns yellow and wilts, and gray blotches appear on the woody parts of the plant.
Flower and Leaf Diseases
The Ciborinia camelliae fungus causes a disorder called camellia flower blight. This issue most often occurs when damp, warm conditions follow a period of cold. Brownish spots appear on the flower petals and rapidly spread across the blossom. The diseased flowers usually fall to the ground within 48 hours, but the leaves and stems are not affected. The Exobasidium fungus causes leafgall. This disorder appears in the spring attacking new plant growth. Emerging leaves are enlarged, thickened and distorted.
Tea scale is one of the most common insect pests to attack camellias, according to Nancy Doubrava and J. McLeod Scott from the Clemson Cooperative Extension. These tiny, grayish-brown insects are less than one-twentieth of an inch in length. They attach themselves to the undersides of camellia leaves and feed on the sap, creating yellow spots. Aphids, also called plant lice, also feed on camellia sap. They leave sticky deposits of a liquid called honeydew, which attracts the sooty mold fungus. Spider mites and mealybugs feed on sap, while weevils, leaf beetles and caterpillars chew on plant tissue and disfigure the foliage.
Camellias that are exposed to full sunlight may develop sunscald. The leaves turn yellow or brown and die. You can avoid sunscald by planting camellias in a location that receives partial shade. Extreme variations in temperature, poor soil drainage or a lack of appropriate nutrients may cause the buds to fall from the plant before they open. Overwatered camellias may also develop oedema, a condition where water builds up in the leaves. Small bumps appear on the stems or undersides of the leaves.