Check these first
- Does the browning start at the leaf edge, from a spot, or from the lowest leaves?
- Are there black specks, powder, or mould on the dead tissue?
- Did you fertilize, spray, or have a heatwave just before it started?
Most likely causes
From the pests and diseases recorded for this plant, the ones whose symptoms match, most serious first. Symptoms alone rarely confirm a cause, so use the linked page to check the signs and treatment.
Bacterial Canker
Leaf margins scorch and die back, and splitting the stem reveals browned vascular tissue. Scabby, bird's-eye lesions form on fruit and shoots.
General description; not specific to this plant.
How to identify and treat: Bacterial CankerLate Blight
Dark green water-soaked lesions appear on the leaves and expand quickly into brown dead tissue. White mold forms on the underside and at the lesion edge, and dark brown lesions spread to stems and fruit.
General description; not specific to this plant.
How to identify and treat: Late BlightSclerotinia Rot
The crown, stem or head rots in a water-soaked way and is covered in white cottony mycelium. Black sclerotia later form inside and on the surface, and the plant wilts and dies.
General description; not specific to this plant.
How to identify and treat: Sclerotinia RotOther possible causes
- Rust — Small raised orange-yellow to red-brown pustules form on both leaf surfaces, then rupture …
- Southern Blight — The stem rots at soil level and white silky mycelium spreads over the crown and the surrou…
- Fusarium Yellows — Yellowing starts on the lower leaves, the petioles twist and the plant leans to one side. …
Other symptoms on this plant
What other growers did about it
A page like this one can tell you what onion leaves turning brown and dying is and what to try. What it cannot tell you is what actually happened to someone who had it on the same plant, at the same point in the season, and what they did next.
Gadenin is a free garden journal built around that. You photograph the plant, tag what you are seeing, and the entries line up by date for each plant you grow.
- Tag the problem and the app tells you how many other growers have logged the same thing on the same plant.
- Growers who make their records public can be followed, so you can read what they did and how it turned out.
- Next season your own entries come back at the same point in the year, so you check the plant before it starts.
Free on iPhone. Recording, tagging and reading public records cost nothing.