Petal Blight of Camellia – Ciborinia camelliae Kohn
Extracts from a great article at The American Phytopathological Society (APS).
- Chemical Control
- The use of fungicides to control this disease is uncommon and should only be used if severe levels of infection are expected based on high disease levels in previous seasons or for high value plantings. Applications can be made as a ground spray or sprayed directly on flowers. Ground applications should be made in the fall or early winter before flowering by drenching the soil around plants. For control, a 10-foot circle of fungicide must be applied to the soil surface around each plant (usually 2 or more quarts). Ground applications prevent apothecia development, so spores are never released to infect blossoms.
- Preventative applications can also be made directly to open flowers. Applications should be initiated when buds begin to show color and repeated based on the labeled fungicide interval. Captan and mancozeb can be used, but are usually not cost effective for use in home gardens.
- Cultural and Sanitation Practices – Cultural and sanitation practices are the most effective for controlling camellia petal blight.
- Once camellias become infected, flower removal can be an effective sanitation practice to reduce inoculum.
- Under camellias already present, the removal of weeds and ground covers can aid in finding and removing diseased flowers.
- Once blooming is over and all flowers have been collected, the top layer of mulch can be raked from under plants and replaced with a 1-2 inch thick layer of new mulch to interfere with spore release the following season.
- Lower branches of each plant can be pruned to increase air flow and create less obstacles for picking up dead flowers from under the plant. Diseased flowers that are collected should be destroyed and should not be composted because sclerotia can survive the composting process.
From the America Camellia Society
Mealy bugs can be controlled through the use of light oil sprays or insecticidal sprays. A strong spray of water will often wash them off the plant. These are not common pests of camellia and therefore are considered relatively unimportant.
Apply two types of controls (read the label and make sure that the active ingredient is different) so the scale insects will not get used to applications of a single insecticide.
- Oil emulsion sprays will give you effective control if applied early in the morning on days when the temperatures are mild (45-85 F).
- Systemic insecticides like Cygon and Orthene can also control tea scale.
- Contact insecticides like Malathion, Dursban and Sevin are very effective but repeat applications may be necessary.