Canker and Dieback (fungus – Glomerella cingulata): Sudden wilting of branches is usually the first indication of disease. Gray blotches appear on bark of stem or branches. Underlying wood dies and bark may split to form open wounds or cankers. Pinkish pustules or spore masses may be seen in these cankers during moist periods. Leaves on affected branches turn chlorotic and branch tips die back. Plant in well-drained soil that has the proper pH and fertility level. Avoid excessive nitrogen fertilization. When dieback occurs, prune out and destroy diseased twigs. Prune several inches below visible canker, and use a commercial wound dressing on all cuts. Spraying plants during wet periods and during the period of normal leaf drop with a fungicide will help control the disease.
Petal Blight (fungus – Sclerotinia camelliae): Petal blight affects only the flower portion of the plant. The first evidence of infection is the appearance of small, brown, irregular-shaped spots on the petals. Affected petals have a “veined” appearance and the tissue remains firm. Entire flower turns brown in 24-48 hours and usually drops. The disease generally occurs during the spring. Remove and destroy all infected plant tissue. Apply fungicide to the soil just prior to bloom to prevent germination of overwintering spores. Thoroughly cover all areas under the plant and at least a 10 foot radius around each plant. Applications of a foliar fungicide at the first sign of disease and at 7-14 day intervals is effective.
Leaf Gall (fungus – Exobasidium camelliae): Young leaves and buds may be infected. Leaves become thickened and succulent and may be larger than normal. The color changes from light green to nearly white. Little damage occurs but the plant appears abnormal or diseased. Pick young galls and destroy. Spray with fungicide before leaves open.
Leaf Spots (fungi – Phyllosticta camelliae, Pestalotia guepini and algae –Cephaleuros virescens): Various sized spots on the leaves. Small, black pinpoint dots may be in the dead leaf areas. Control requires preventive fungicidal sprays at two week intervals. Include a spreader sticker to increase effectiveness of sprays.
Ring Spots (virus): Occurs mostly in East Texas. Light green or yellowish rings surround islands of green in the leaves. Destroy diseased plants. Propagate from disease-free plants.
Yellow Mottle Leaf (virus): Irregular, yellow patterns on some leaves. No cure available. Propagate from disease-free plants.
Bud Drop (physiological): May occur as a result of overwatering, inadequate moisture in the soil, insufficient light, excessively high temperatures, severe freezing during the winter or a pot-bound condition of the roots. Also, certain camellia varieties shed their unopened bloom buds as a result of insufficient cold during the winter. Fertilize and water properly. Keep plants healthy by controlling diseases and insects.
Oedema or Scab (physiological): Corky bumps or raised areas on leaves. Usually due to excessive water in soil.
Sunburn (physiological): Leaves have brown or faded green areas. Occurs on side of bush directly hit by the sun. Particularly a problem on bushes transplanted from a shaded to a sunny location.
(physiological): Margins of leaves turn light brown and dry. Camellias cannot tolerate high soil salinity.