Diseases of a Camellia With Curled Yellow Leaves

Yellow Mottle Virus

• Yellow or white mottling on camellia leaves indicates the presence of a virus, commonly called yellow mottle virus. Spread genetically, through grafts and propagation practices, yellow mottle virus is not spread by any known vector, such as insects, wind dispersal or contact with infected plants. Instead, the virus lives within plant tissues. The virus can lie dormant, producing symptoms during the growing season from spring through fall. Yellow mottle virus does not affect plant vigor, and it sometimes disappears on its own. Although viruses generally cause leaf curl or distortion, yellow mottle disease does not distort leaf shape. Prune out mottled branches 3 to 4 inches below the infection if you consider the yellow leaves unsightly.

Canker Disease

• A canker disease caused by the fungus Glomerella cingulata can destroy your camellia plant if left untreated. Presence of the disease can go unnoticed until leaves of affected branches turn yellow and wilt. Spread by spores, this fungus enters healthy plant tissue at leaf scars, pruning wounds or grafts, according to the Alabama Cooperative Extension System. Fungal cankers develop on the trunk and shoots of infected plants, splitting the bark and releasing spores after a rainy spell. Stress from heat and drought can exacerbate the development of the disease. Remove affected branches. Make certain to sterilize your pruning shears with isopropyl alcohol or a similar disinfectant.

Root Rot

• Root rot affects Japanese camellias (Camellia japonica), causing yellow leaves and stunted growth. Caused by the fungus Phytophthora cinnamomi, infected root systems lead to plant wilting and death. Fungicides containing etridiazole or mefenoxam help prevent development of the disease but do not cure affected plants. The best way to combat root rot is through cultural practices, such as providing well-draining soil. If you live in a location in which root rot is prevalent, plant the nonsusceptible sasanqua camellia (Camellia sasanqua) or a Japanese camellia grafted onto sasanqua camellia rootstock.

Culture

• Japanese and sasanqua camellias grow in U.S. Department of Agriculture plant hardiness zones 7 through 9. But cold-tolerant hybrids, bred from Camellia oleifera "LuShan Snow" and Camellia oleifera "Plain Jane," that grow in USDA zones 6 through 8 can be planted in northern climates on the north side of a wall or sheltering hedge and when given protection from morning sun and winds. Shallow-rooted camellias grow best in raised beds with well-draining, acidic soil. A mulch of pine needles or other organic material keeps the roots uniformly moist and cool. Avoid placing mulch right next to the trunk. Fertilize in March, May and July with 1 tablespoon of a general purpose fertilizer -- such as 8-8-8 or 10-10-10 -- for every foot of plant height.