I'm a newbie in gardening, and my tomatoes always seem to die from the same disease, which I couldn't identify.
It typically starts from the bottom of the plant and gradually affects the entire plant, until it dies.
First the leaves dry, and then the stem (as can be seen in second picture), which feels like hollow after some time.... Anyone has some idea of what I should do to stop or prevent this phenomenon in the future? I live in South California.
Thank you for your help!