Petal Blight and Camellias
January 11th, 2021 by Meredith Heroux
In the South, we are blessed with so many broad-leafed evergreens but Camellias are probably the most popular. These evergreen shrubs are highly prized for their dark green waxy leaves and large colorful flowers. Camellia species originated in Asia, where they have been used in numerous cultures for centuries. Camellias are popular ornamentals and some species can be used commercially to make tea (C. sinesis L.), while others are used as oils for cosmetics and cooking (C. oleifera Abel). In the landscape, camellias can be accent plants, used to form hedges and borders, or pruned for growth as small trees. Flowers range in size, color, and form. The three most popular ornamental camellia species include Camellia sasanqua Thunb., C. japonica L., and C. reticulate Lindl. There are additional species and over 20,000 registered hybrids of camellias, most of which are known to be susceptible to petal blight. In the United States, camellias are widely grown in the southeast, and the Pacific and Gulf coasts.
Petal blight is caused by the ascomycete fungus Ciborinia camelliae. The pathogen infects flowers soon after they begin to open (December through April for us in the South). Infected blossoms turn brown and fall to the ground, and while severe infections can significantly decrease the aesthetic appeal of plants in the landscape, the disease is not harmful to the long-term health of the plant.
It looks like cold damage. The blooms will turn brown and there could be brown spots. Soon after these lesions appear, the blooms will fall off or not open at all.
Cultural and Sanitation Practices
What can you do to prevent petal blight affecting your Camellias? It’s really quite simple, remove the spent blossoms that have fallen to the ground. Those blossoms harbor the fungus that splash up, into and on the leaves of your Camellia. We have well over a hundred in our collection and right now, removing fallen blossoms is our number one priority. By removing the blooms, you are removing the inoculum. Once you have done this, it’s a good idea to remove last years mulch, which could harbor the fungus, and replace with fresh. There are fungicides you could use but we do not recommend them as they are toxic to the environment and expensive. For the home landscape, you could wait until all the blooms have fallen and remove them all at once. 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.
We are part of Georgia’s Camellia Trail which consists of 30 gardens all across the state that have wonderful collections. For more information about Georgia’s Camellia Trail, visit Explore Georgia’s article.
The Camellias of SGG are planted throughout the gardens but the bulk of them can be admired in the ¼ acre Paladino Camellia Garden located along the woodland trail. Come see for yourself why Camellias are the Souths favorite evergreen.