Tomatoes don't like rain

A shelter helps against the rain, because tomatoes, just like potatoes, are very sensitive to the pseudo fungus Phytophtorah .
As soon as brown spots appear on leaves and stems, the tomato hasdisease (Phytophthora) has emerged. This water fungus causes the characteristic black spots on the leaves of potatoes and tomatoes. They are fungal-like microorganisms.Late blight hibernates on remaining plant remains and in the soil. Contamination is caused by insects, spores carried by wind and rain and in splashing water. During periods of summer, hot and humid weather, Phytophthora can do great damage in a short period of time.
To prevent disease, tomatoes are aerated. In professional fruit cultivation, it is monitored how long the leaves remain wet (wet leaf period) and what the temperature is. The combination of both is partly responsible for the development of Phytophthora. Well-drained soil helps prevent Phytophthora: Moisture encourages germination of spores.

recognize late blight in patatoes
A potato leaflet showing late blight infection caused by Phytophthora infestans, photo: Howard F. Schwartz - CC BY 3.0

Phytophthora is not limited to potatoes and tomatoes only. Roses, for example, can suffer from root rot caused by phytophthora is caused. Silver firs, such as the Nordmann fir, can also be affected by phytophthora get root rot, causing the spruce to dry out and die.