Yellow shoulders: what do I do?
Q. My tomatoes won't ripen up around the shoulder area. I have all that waste when I am canning. What can I do to prevent yellow shoulders or green shoulders on tomatoes?
A. The main reason tomatoes (no matter what variety) develop yellow shoulders is that lycopene production is inhibited in the upper portion of the fruit. Lycopene is a plant pigment which gives tomatoes their red color. The most common reason for the inhibition is too much heat or sunlight on tomato tops. Ideal temperatures for lycopene development is 65-75 degrees. Of course, many gardeners tolerate higher temperatures than that throughout the summer.
As sun strikes tomatoes, temperatures rise, inhibiting lycopene. But carotene, another pigment in tomatoes which produces yellow and orange, is less affected by heat. Higher temps penetrate the tomato tops, allowing carotene to shine through. Meanwhile, lycopene is squelched. Thus your tomatoes' shoulders remain yellow while the rest of the tomato ripens to red.
- Maintain good leaf cover if possible. Plant more densely and prune less.
- Shade plants in the afternoons when temperatures are especially hot and fruit is ripening.
- Some tomato varieties have inherited more of a tendency to green or yellow shoulders than others. Choose varieties that are less apt to be slow-ripening on their tops.
Keep in mind that certain varieties (like Cherokee Purple Tomato) naturally ripen with green shoulders.
Good luck and happy gardening!Your friends at Tomato Dirt