Control Measures of Citrus Canker Disease

Canker disease is a serious bacterial disease that affects citrus plants, causing significant damage to leaves, fruits, and stems. It is caused by the bacterium Xanthomonas citri subsp. citri, which can spread rapidly through wind, rain, and infected tools or equipment. Citrus canker is most severe in hot, wet areas. The infected sites ooze sap which can carry the disease from tree to tree by irrigation or rain splash. Citrus canker can spread quickly over long distances on infected citrus fruits and leaves, as well as on people and equipment. The bacteria that cause citrus canker enter leaves through stomata, or through wounds caused by weather damage or insects, such as the citrus leaf miner (Phyllocnistis citrella). Young leaves are the most susceptible. Symptoms generally appear within 14 days of exposure to the canker bacteria. The bacteria remain viable in old lesions and on plant surfaces for several months. 

Identifying Canker Disease in Citrus Plants:

On Leaves:

• Small, raised, yellow spots: These initial lesions appear on the underside of leaves, typically around 7-10 days after infection.
• Spots enlarge and turn brown/corky: As the disease progresses, the spots grow up to 2-10 mm in diameter, becoming raised, brown, and corky with sunken centers and raised margins.      
• Yellow halo surrounding lesions: A distinct yellow ring often surrounds the canker spots, making them easily identifiable.
• Lesions visible on both sides: Eventually, the lesions become visible on both the upper and lower surfaces of the leaves.

On Fruits:

• Similar lesions as on leaves: Fruits develop canker spots with similar characteristics as those on leaves, affecting their appearance and marketability.

Classification:

• Type of Infestation: Disease
• Common Name: Cancer
• Scientific Name: Xanthomonas campestris pv citri
• Category of Plant Disease: Fungal Disease
• Mode of spread: Wind, Rain, Water and contaminated seeds
• Affected parts of plant: Leaves, Fruit

Favorable factors for disease/Pest Development

• Warm and humid weather: The bacteria that causes canker disease thrives in warm temperatures (between 25-30°C) and high humidity (above 70%). These conditions encourage bacterial growth and survival, making infection more likely.
• Rainfall and wind: Heavy rain and strong winds can splash and disperse the bacteria from infected leaves, fruits, and twigs to healthy trees, facilitating the spread of the disease.
• Presence of standing water: Standing water around the base of the tree creates a humid environment favorable for bacterial survival and spread.

Control Measures of canker disease