Camellias are flowering shrubs native to Asia. Ubiquitous symbols of the South, these plants are desirable for their huge, attractive, fragrant blossoms. There are many species and cultivars of camellia, but the most common is C. japonica, according to the University of Florida. Although popular, camellias are not known to be hardy plants. Not only do they have specific culture requirements, but they also are susceptible to a number of insect pests and diseases.
Scales are tough little insects that cling to the undersides of the leaves of the camellia. Tea and camellia scale are two of the most common. Large infestations of scale are difficult to get rid of, according to the University of Florida, so it is important to catch the insects when their numbers are small. Treat these minor infestations with an insecticide recommended for scale removal.
Aphids, like scales, love to suck the juices from the leaves of the camellia plant. Affected leaves tend to curl up or become deformed. These tiny green or white insects excrete honeydew, which is very sticky and can attract ants. Fungal spores easily stick to honeydew, which leaves the plant open and vulnerable to fungal infections such as sooty mold. For these reasons, it is important to get rid of aphids as soon as you notice them. Use an insecticide approved for aphid control, and apply it according to the directions on the label for the size of your camellia plant.
Root rot is a fungal disease that occurs when the soil around the shallow roots of the camellia plant becomes and remains overly saturated with water. Too much water in the soil leads to the rapid development of fungal spores. The type of fungus that affects camellias is Phytophthora cinnamomi. The fungus attacks and invades the feeder hairs of the camellia, causing the roots to become unable to absorb nutrients and water. The plant’s growth slows, the leaves turn yellow and the camellia experiences an overall decline and failure to thrive. In time, the plant will die.
Once symptoms appear, it is difficult, if not impossible, to save the plant. Root rot can be avoided by planting the shrub in very well-draining soil and making sure not to over-water the plant. Preventative fungicides, or soil drenches, can be used in the spring, but these will only prevent, not cure, the disease.
Camellia Dieback and Canker
This disease is a serious problem in camellias, according to Clemson University. The cause is a fungus (Glomerella cingulata). The fungus can enter the plant through minor wounds, infected pruning tools or in the soil. Affected plants will show sudden yellowing of the leaves and experience dieback, which means they begin to die from the tips of the twigs inward. Cankers--dark, sunken areas of dead wood--develop on the branches. If the cankers girdle the stem (go all the way around it), the nutrients are cut off, and that part of the plant will die.
Prune off areas that have cankers or yellowing leaves. Make sure the soil around the camellia is not overly wet, which can cause fungal growth. Disinfect pruning tools and take care not to wound the camellia with yard tools, such as when mowing around a bush. Fungicides can be used as a preventative measure. They should be applied during the normal leaf drop time according to the instructions on the label.