|Hard, unripe patches on tomatoes signal tomato greenback
Image: University of Connecticut Home and Garden Education Center
Tomato greenback is a physiological problem caused by stress to the plant, rather than a pest or disease. It usually affects greenhouse-grown tomatoes and causes hard, green areas to form on the fruit that make it unpleasant to eat.
When tomatoes begin to develop and ripen, the fruits, stems and leaves require a sensitive balance of water, light and nutrients. Greenback is usually caused by excessive heat in the greenhouse, exacerbated by a lack of potassium. The result is hard green patches that fail to ripen properly on the stalk end of the tomato.
|You can grow greenback resistant varieties
Image: Tomato 'Nimbus' from Thompson & Morgan
There’s no treatment for tomato greenback once it develops, but there are several things you can do to prevent your tomatoes suffering from stress:
Should your tomatoes develop greenback, the ripe parts of the fruit can still be eaten. Simply remove the dark, unripe sections and discard. You can also try growing greenback resistant varieties such as ‘Alicante’, ‘Cristal’, ‘Nimbus’ and ‘Craigella’.