Petal Blight

Petal blight is a type of fungal disease that attacks rose, azalea and camellia blooms. Petal blight can occur after a rainy season or when overhead irrigation is used.

Fungal diseases are difficult to manage. A single fungi can produce 60,000 spores on a piece of plant tissue smaller than a dime. A single spore is all that is needed to infect a plant. It’s a numbers game and the odds are in favor of the fungi - unless you implement good cultural practices.

Camellia petal blight

Camellia petal blight is caused by the Ciborinia camelliae fungus. Symptoms begin as brown lesions that darken at the centers first. Petal veins may darken and blossoms drop prematurely.

Azalea petal blight

Azalea petal blight is caused by the Ovulinia azaleae fungus. It first shows as small brown water-logged spots that grow larger and slimy. Within 2-3 days, flower petals are limp and icky. These fungal breeding grounds will dry out but remain on the plant. Remove infected sections of the plant carefully and remove from the site.

Petal blight of roses

Roses are particularly susceptible to Botrytis Blight, also known as Gray Mold. Stems, canes, leaves, buds, and petals can all be affected. Similar to Azalea petal blight, symptoms begin as small soggy spots. These spots may have a red border. Petals can become stuck together, preventing buds fro opening. As infestation spreads, infected areas become covered with a gray fuzz that is a fungi’s vegetative state, called mycelium. African violets, grapes, and many other plants may also become infested.

Petal blight control

Fungicides are generally ineffective against petal blight, so it is best prevented with good cultural practices. These tips can reduce fungal spore survival: 

• Dispose of diseased blooms immediately.
• Remove all fallen plant material from the infested plant - do not add it to the compost pile.
• Mulch with 4” of aged compost under affected plants without disturbing older layers of mulch.
• Avoid overhead irrigation.
• Ensure that the soil is properly aerated.​​