How do bacterial toxins produce leaf spots stem blights and cankers?

Bacterial pathogens produce symptoms such as leaf spots, stem blights, and cankers by secreting toxins (poisons) that induce necrosis in plant tissues.1

When these bacteria infect a host, the released toxins damage or kill the plant cells, leading to localized areas of dead tissue. These necrotic areas manifest as:

• Leaf spots: Localized lesions on the foliage.12
• Stem blights: Areas of rapid dieback or tissue death on stems.12
• Cankers: Sunken, swollen, or cracked dead areas on stems, twigs, or trunks that can eventually girdle and kill branches.13

While these symptoms are primarily driven by toxin-induced necrosis, other bacterial diseases may involve different mechanisms, such as the secretion of enzymes that cause soft rot or the manipulation of plant cell growth to form tumors.1