Citrus canker disease is an isolated threat in the cold-hardy citrus region that growers should remain aware of.
Jonathan Oliver, University of Georgia (UGA) assistant professor and small fruits pathologist, recently discussed the disease and its potential impact in cold-hardy citrus.
“Canker has been found in Georgia, as reported several years ago. It seems to be very isolated in a few areas,” Oliver said. “It is still a concern that it may spread from those groves, because it can easily move around on equipment, personnel and any plant material.”
Oliver said those who should be most concerned about the disease are any producers growing citrus near the areas where canker has been previously found.
“Satsumas and other mandarins, which is most of our acreage in Georgia, are largely resistant to canker,” said Oliver. “However, wounding caused by insect feeding, especially leafminer damage, can provide an entry point where even those resistant varieties can become infected.”
The disease needs only water or air to spread. Symptoms can appear on the fruit, leaves and twigs. Small blister-like lesions with water-soaked margins and yellow halos can form on both sides of a leaf. The best way to prevent the disease is for growers to ensure they purchase trees from a certified nursery.
Oliver also cautioned growers against misdiagnoses of the disease. He advised using specialists who can properly identify the disease in a research lab.
“You can somewhat distinguish canker based on symptoms. But ultimately, it is better to have it officially tested and confirmed. There’s a lot of overlap of symptoms that can be caused by canker bacteria versus different fungal organisms,” Oliver said. “For an untrained eye, it can be easily mistaken. Even a trained eye can sometimes get it wrong.”
Learn more about citrus canker here.
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