Blotchy ripening and yellow shoulders
Not an infection: ripening is disrupted by heat or weather stress, often with too little potassium
| Type | Not an infection |
|---|---|
| Cause | Not an infection: ripening is disrupted by heat or weather stress, often with too little potassium |
| When | Mid to late summer, after heat spells or sharp weather changes. |
About
Tomatoes that ripen unevenly, with hard yellow or green patches, especially around the stem end. Leaving them on the vine longer does not fix it.
Also called blotchy ripening, yellow shoulder, yellow shoulders, graywall, gray wall, uneven ripening, white tissue, internal whitening
How to recognize it
Symptoms
With yellow shoulders, the top of the fruit around the stem stays yellow-green and hard while the rest turns red, and the flesh under it can be white and tough. Blotchy ripening leaves green, yellow or gray patches scattered over the fruit, sometimes with dark, dead tissue inside the walls (graywall).
Often confused with
Sunscald makes a pale, papery patch that later sinks, on the side facing the sun. UMN notes plant viruses may also play a part in yellow shoulders (see Mosaic viruses).
Worse when
Heat at or above about 90°F, hot weather right after a cloudy, rainy spell, low potassium, soil pH above about 6.7, varieties with dark green shoulders, open canopies (yellow shoulders) or dense, shady canopies and cool, short days (blotchy ripening).
How it spreads
It does not spread.
When
Mid to late summer, after heat spells or sharp weather changes.
What to do, gentlest first
This is not an infection, so sprays for diseases won't help. Fix the cause below.
Soil test and feed potassium by the results Prevent
Test the soil before planting and add potassium and lime only as the test calls for. Keep soil pH around 6.4 to 6.7.
Feeding potassium after symptoms show is unlikely to help this year's fruit.
Try another variety Prevent
If one variety keeps getting yellow shoulders, grow a different one next year; varieties with dark green shoulders that lack the uniform-ripening trait are the most prone.
Balance the leaf cover Prevent
Keep enough leaves to shade the fruit without making a jungle: yellow shoulders are more common in open plants, blotchy ripening in very dense ones.
Cut away the hard parts By hand
Pick affected fruit and cut away the hard, pale parts when you use it.
Plants it affects
Sources
Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.