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- Leaf gall cropping up on camellias, azaleas in Louisiana
Leaf gall on camellia causes leaves to become distorted and thickened with a fleshy or leather-like texture. Photo by Raj Singh, LSU AgCenter
Leaves are distorted and become thickened with a fleshy or leather-like texture when leaf gall infects azaleas. Photo by Raj Singh, LSU AgCenter.
An older, mature gall turns brown on an azalea. Photo by Raj Singh, LSU AgCenter.
(04/25/16) BATON ROUGE, La. – As the summer growing season gets into full swing, pathogens that cause plant diseases also are cropping up.
Extended periods of cool, wet weather during spring have led to several plant diseases in commercial and home gardens, according to LSU AgCenter plant pathologist Raj Singh.
One of these diseases is leaf gall of camellia and azalea. “This is primarily a leaf disease, but occasionally it may occur on stems, flowers and seed pods,” Singh said.
Two species of Exobasidium fungus cause this disease, one on azaleas and the other on camellias.
Symptoms of leaf gall start appearing soon after the plants finish flowering, Singh said. Leaves are distorted and become thickened with a fleshy or leather-like texture.
Galls tend to be pale green, pink or white in the beginning, he said. But as they develop, the galls become white and powdery. “The white powder material is the spores of the fungus, which readily disperse via air currents and by splashing water,” Singh said.
As the galls get older, they shrivel up, dry out and turn brown and hard. “Older galls fall to the ground, where they survive and may serve as a source of infection the next spring’s growth,” he said.
Leaf gall can be managed primarily by adopting good cultural practices in the landscapes.
“Proper pruning and discarding of galled leaves is very important in reducing the spread of the disease,” Singh said.
Cut galled leaves couple of inches below the symptoms, and before discarding them, put them in plastic bags. Remove and destroy affected leaves with galls that have fallen on the ground.
“Selectively thin the canopy of established plantings to improve air circulation and promote rapid drying of foliage,” Singh said. “And maintain adequate spacing when establishing new plantings to avoid creating favorable conditions for disease development.”
Fungicides may help avoid infection when applied beginning at bud break, he said. Repeated applications may be required every 10 days as long as the conducive weather conditions persist for disease development.
For fungicide recommendations, consult your local AgCenter parish agent.
More information on leaf gall of azalea and camellia also is available from Singh at 225-578-4562 or email rsingh@agcenter.lsu.edu.