The swelling of tomatoes: why tomatoes are hollow on the inside

The tomato is the first plant grown in the garden, but for many gardeners it also seems to be the first to suffer from diseases and problems. Some of the rare and unusual problems that the tomato develops are the hollow fruit of the tomato and the hollow stems of the plants. These two very different problems have different causes, even though at first glance they seem similar.

Why are tomatoes hollow inside?

Tomato fruits can end up hollow if they have not been fully pollinated as flowers or if something could not develop at the beginning of the seed. This happens for a variety of reasons, including inadequate temperature or excessive rainfall that can hinder pollination activity, or inadequate fertilization, especially when nitrogen levels are high and potassium low.

Hollow fruit, also known as tomato swelling, cannot be reversed in fruits that are already developing, but future fruits can be protected by doing a soil analysis before fertilizing. Environmental conditions that discourage pollinators are difficult to control, but most swollen tomatoes disappear as the season progresses.

Some special varieties of tomatoes have been grown to be hollow inside and should not be confused with tomatoes that suffer from swelling. These stuffed tomatoes are available in a wide range of sizes, shapes and colors and often carry the words «stuffed» or «hollow» in their name. Varieties such as Yellow Stuffer, Orange Stuffer, Zapotec Pink Pleated and Schimmeig Striped Hollow will always be hollow, despite your best efforts.

How to avoid a hollow tomato plant

When the tomato plants are hollow, it is a totally different and very serious situation. The bacterial pathogen Erwina carotovora causes bacterial stem rot, a disease that causes the pith of the tomato stem to disintegrate. Tomato pith necrosis is caused by the bacterium Pseudomonas corrugata , but it behaves in the same way as bacterial stem rot. Ultimately, these diseases are difficult to detect as long as the plant is not too far away to be saved.

If your plants turn yellow and appear wilted, check the stems carefully for dark or soft areas. Areas that break off easily or fall off during inspection are likely to be empty. Destroy these plants immediately to prevent the spread of disease. In the future, plants should be spaced further apart to promote better air circulation and pruned carefully. Stop using nitrogen fertilizers, as pruning wounds are often the site of infection in bacterial stem diseases.