Yellow V-Shaped Spots on Cole Crops: Black Rot
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GardenSays
Best match: Black rot. Manageable if you act.
- Best match
- Black rot
- Severity
- Act soon
- Causes checked
- 1
Based on yellow or dark v-shaped spots at leaf edges on the lower leaves with moist soil, the closest match is black rot. Confirm it against the actual plant: Yellow, V-shaped (triangular) lesions starting at the leaf margin, sometimes with blackened veins visible inside the V.
- This is a symptom-pattern match from your written description, not a lab diagnosis. If the plant is collapsing over days (not weeks), treat it as the worst plausible cause until ruled out.
Do this this week
- 1.Confirm it first: Yellow, V-shaped (triangular) lesions starting at the leaf margin, sometimes with blackened veins visible inside the V.
- 2.No cure. Remove affected leaves/plants; avoid overhead watering and working plants when wet; rotate cabbage-family crops out of that bed for 3-4 years.
- 3.Collapsing fast (days, not weeks)? Photograph it and check with your county extension before treating
Calculated result · 2 verified sources · Checked 2026-07-17 · How we decide
Why
What to do: No cure. Remove affected leaves/plants; avoid overhead watering and working plants when wet; rotate cabbage-family crops out of that bed for 3-4 years.
- A symptom tree ranks causes by how well your conditions match each cause's known pattern — the distinguishing signs are how you confirm it on the actual plant, not a lab result.
- Most leaf problems trace to water, weather, or common leaf-spot fungi; true plant-killers are rarer but worth ruling out first.
When this doesn't apply
- If the plant is collapsing fast (days, not weeks), treat it as the most severe possibility on the list until proven otherwise.
- Multiple symptoms at once usually means the top cause here plus plain stress — fix watering first, then re-check.
How this was calculated
- 1. SymptomSource guidance
Cabbage: yellow or dark v-shaped spots at leaf edges — 1 known cause evaluated (extension-sourced)
- 2. Your conditionsCalculated result
Location on plant: lower; soil: moist. Causes whose known pattern matches these conditions rank higher — this narrows the list, it doesn't identify anything.
- 3. 1. Black rotmatch score 1Calculated result
Distinguishing signs: Yellow, V-shaped (triangular) lesions starting at the leaf margin, sometimes with blackened veins visible inside the V.
Data sources
- University of Minnesota Extension — Caterpillars on cole crops — Imported cabbageworm: velvety green with faint yellow stripes, up to 1 inch, most common cole-crop caterpillar. Cabbage looper: light green, up to 1.5 inches, moves with a distinctive looping action. Diamondback moth: small, smooth caterpillars that create many small holes. Young caterpillars make small holes that don't break the upper leaf surface; larger caterpillars chew large ragged holes, leaving large veins intact. (checked 2026-07-17)
- University of Minnesota Extension — Black rot of Brassica crops — Black rot causes yellow, V-shaped/triangular lesions at the leaf margin and can rot cauliflower crowns; most damaging in broccoli, cabbage, cauliflower and kale. Bacteria enter through leaf-margin pores (hydathodes) where morning dew collects, or through wounds. (checked 2026-07-17)
What changes this answer
Where on the plant?
Soil right now
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