Citrus canker is caused by a bacteria that penetrates citrus trees through stomata or wounded tissue.The disease favors high humidity that is combined with warm weather conditions. Citrus canker can spread by winds, rain or water splashes, and it can be transmitted mechanically through using contaminated tools.
Initial symptoms of citrus canker are small lesions on leaves that might resemble blisters. Later on, the blisters develop into brownish necrotic-like elevated corky lesions often surrounded by a yellow halo. On twigs, citrus canker appears corky, which is often surrounded by water-soaked margins. On fruits, citrus canker appears as brown scab-like or corky lesions and appear as elevated tissue.
Generally speaking, once a tree is infected with the bacteria, the tree begins to slowly decline towards the death. The fruits and foliage tend to drop prematurely and infected fruits that have canker signs are not marketable. Citrus canker has the ability to decimate entire orchards and poses a huge risk to the whole citrus industry.