Quick guide to insects and diseases of onions
This page highlights non-chemical practices to prevent or manage common insect and disease problems of onions.
For more detailed information follow the links in each section.
Click on an image to enlarge it.
- Remove weeds and plant residue.
- Till garden before planting.
- Place cardboard collars or aluminum foil around plant stems when planting transplants.
More information on cutworms.
- Avoid using animal manure or green manure in spring.
- When possible, delay planting onions until after June 1.
- Remove and destroy host plants in fall.
- Cover plants with a row cover (light weight fabric) in spring.
- Don't plant onions in the same area in consecutive years.
More information on onion maggot.
- Yellow storage onions are more resistant than Spanish onions.
- Use drip irrigation.
- Don't leave culls near field.
- After harvest, remove and destroy or bury any infected leaves.
- Don't plant onions, leeks or shallots in the same field for 3-4 years.
Fusarium basal rot
- Plant varieties with tolerance or resistance to disease.
- Plant in well drained soil or use raised beds to improve drainage.
- Don't plant onions, shallots, garlic or chives in the same field for 4 years.
Reviewed in 2019