Center rot

Center rot is a destructive bacterial plant disease primarily caused by Pantoea ananatis. As a systemic bacterial infection, it affects the internal structure of bulb crops, making it a major concern for growers who supply both fresh markets and long-term storage facilities.

The disease is most commonly observed in onions and garlic. It can devastate entire fields if environmental conditions favor rapid bacterial multiplication, leading to significant post-harvest losses when the internal breakdown of the bulb becomes irreversible.

Symptoms typically begin with leaf lesions that may appear water-soaked or necrotic. As the infection moves downward, the center of the onion bulb becomes soft and develops a distinct brown or black discoloration. In advanced stages, the internal layers liquefy, leading to total tissue collapse and a foul odor.

Development and spread are accelerated by warm, humid weather and heavy rain. Bacteria are spread by splashing water, infested debris, and most importantly, through insect vectors like thrips that cause necrotic feeding wounds. These wounds provide a direct pathway for the bacteria to enter the plant vascular system.

Integrated management is essential for control. Growers should prioritize the use of disease-free sets, manage thrips populations aggressively with insecticides, and practice crop rotation. Post-harvest, ensuring rapid drying and curing of bulbs at appropriate temperatures is critical to limit the progression of rot during storage.