The changeable weather of this summer was an issue for tomatoes. According to data from the Chamber of Agriculture North-Rhine Westphalia most damages are split open fruits, or fruits with apical-blossom end rot. Some tomatoes show yellow or green shrouds or so-called gold-dots.
The tomatoes are splitting open in a circular manner when the shoot tips are removed or when very hot days are followed by a rainy period. When the weather is hot, the plants are aiming to take in as much water as possible, if the weather then changes to rain there may be too much pressure on the skin and the fruit will split open. To prevent this, the plants should be watered less when the weather is frequently changing.
When the fruits are not ripening fully, it is called yellow or green shroud, caused by too much sun exposure. Other stressful factors, such as sporadic heat periods or a semi-ideal availability of nutrients can intensify the problem. In this case, plants should be shaded.
Apical-blossom end rot is a grayish-brown discoloration of the lower end of the fruit. This is caused by a shortage of calcium due to low pH levels. It can also be caused by too high levels of ammonium, potassium, magnesium and sodium, which can hinder the absorption of calcium and cause the end rot. Another possibility is when the soil is constantly too dry.
When the skin of the fruit is covered in tiny yellow/gold spots, there were too many calcium crystals stored in the skin. This can be caused by high root pressure, a wrong ratio of calcium and potassium or unfavorable air humidity.
Source: Chamber of Agriculture North-Rhine Westphalia