Onion Pink Root

Phoma terrestris, a fungus

Host Plants:

On Crops: Onions, garlic, and numerous vegetables and weeds

Where Found:

Mostly in warm summer climates


Onion plants begin wilting at the leaf tips, and gradually die back before they are fully mature. If you pull up an affected plant, many roots will be rotted, but there may be a few pink ones among the roots that remain. Pink color may also be present in the soft outer layers of infected onion bulbs. This disease is most common in summer when temperatures are above 80F (27C).


As pink root destroys onion roots, the plants cannot keep leaves supplied with moisture and nutrients, so they die. Bulbs may be small and immature. Bulb onions infected with pink root often rot in storage.

Preventing Problems:

Always rotate onions with non-related crops. Grow onions in fertile, well-drained soil. As bulb onions gain size, taper off on watering so the soil stays somewhat dry.

Managing Outbreaks:

Pull up affected plants and trim them for immediate consumption, and compost the trimmings in an active compost pile.

< Back