Camellias are the delight of the gardener who desires a little blooming color in the cooler months. These hearty evergreen shrubs perform especially well in the deep South where the winters are mild. However, a few diseases and pests are typical foes of the camellia. Knowing the most common diseases and pests and tips for controlling them will help you have beautiful camellias.
Flower blight is the result of a fungus called Ciborinia camelliae. Small brown spots appear on the petals and quickly grow to cover most or all of the bloom. Typically, the surrounding green foliage maintains a healthy appearance. Flower blight can sometimes be confused with other problems like excessive sun or wind. However, these conditions usually cause browning on the edges of the petals, whereas flower blight spreads toward the center of the entire bloom.
Controlling flower blight requires good sanitation. Remove and destroy all infected flowers, including those that may be lodged in the branches or on the ground. Replace the mulch under the plant because the fungus thrives in soil. Additionally, it may be necessary to treat neighboring plants because fungus spores can travel up to a mile on the wind. For severe cases, the use of fungicidal sprays and soil drenches may be needed to suppress the disease.
Leaf gall is another problem caused by a fungus, and it tends to be more common on the sasanqua varieties of camellia. It is usually noticed during the early spring growth as some new shoots take on a fleshy, abnormal appearance. The affected foliage turns a pale pink or white shade and eventually ruptures on the underside of the leaves to release spores.
Much like with flower blight, controlling leaf gall requires removing and disposing of affected foliage, including that which is already on the ground. Chemical controls are most effective if applied when the buds first break, continuing through the spring until June. Read the label instructions for the fungicide you choose for more specific application guidance. Also, avoid wetting foliage when watering because the fungus thrives in moist conditions.
Scale is an infestation of insects that feed off and damage camellia leaves. Signs of scale include a white, cottony substance on the underside of leaves and a yellow mottling of color on the tops of leaves. Scale can reduce flower number and size, cause leaf drop and in severe cases can kill the plant.
Small infestations may be controlled by scraping the bugs off the bottoms of leaves or removing affected leaves altogether. For more serious problems, follow those steps with the application of a horticultural oil designed to eliminate scale. Repeat applications will probably be necessary, and be sure to spray the underside of leaves where the insects and their eggs are found.