Camellia Dieback & Canker: This is one of the most serious of all camellia diseases and is caused by the fungus Glomerella cingulata. Normally only a few leaves show symptoms, which can range from a few spots to almost the whole leaf being yellow. When infected, leaves appear speckled with a silver or bronze cast. To confirm the presence of botrytis turn the affected flower over and look … Leaves on affected branches suddenly turn yellow and wilt. Branch tips usually die. Mites are typically most active during spring and fall when the weather is cool. It causes premature aging of blooms and brown spots especially in the centre of flowers. Parts of the plant above the stem canker lose vigor, wilt, and die. Spider Mites are a common, but serious pest of many ornamental plants, including camellia. Yellow leaves can indicate that a plant is suffering from a nutrient deficiency or is affected by cold weather, but yellow blotches on camellia leaves are often caused by a virus. Botrytis (Grey Mould) This is one of the most common airborne fungal diseases affecting camellias. Damaged plants show more symptoms … Some control may be had by spraying the plant with water, but usually chemical controls will be more effective. Gray blotches appear on the bark and stem, and then sunken areas (cankers) develop, eventually girdling the stem.