Slippery skin disease of onion
Causal Agent: Burkholderia gladioli pv. alliicola (syn. Pseudomonas gladioli pv. alliicola)Symptoms:
- Field symptoms often appear as one or two wilted leaves in the center of the leaf cluster.
- These leaves eventually turn pale yellow and dieback from the tip while older and younger leaves maintain a healthy green appearance.
During the early stages of this disease, the bulbs may appear healthy except for a softening of the neck tissue.
- In a longitudinal section, one or more inner scales will look watery or cooked.
- The disease progresses from the top of the infected scale to the base where it can then spread to other scales, rather than by spreading crosswise from scale to scale.
- Eventually, all the internal tissue will rot. Finally, the internal scales dry and the bulb shrivels.
- Squeezing the base of infected plants causes the rotted inner portion of the bulbs to slide out through the neck, hence the name slippery skin.
- Harvest onions when bulbs have reached full maturity.
- Do not store bulbs until they have been properly dried.
- Minimizing stem and bulb injury and avoiding overhead irrigation when the crop is approaching maturity can reduce losses from this disease.
- Bulbs should be stored at 0-2°C (32-36°F) with adequate ventilation to prevent condensation from forming on the bulbs.