Q: This year I decided to try my luck at growing a few tomato plants. They are in containers and have done quite well since Easter. However, now the lower leaves are turning yellow and on one of them strange root-like growths are appearing on the lower stem. I would love your suggestions. I was looking forward to nice home-grown tomatoes this summer!
A: One of the talents of tomatoes is their ability to form adventitious roots along the stem. Experienced gardeners always plant their tomatoes deeply, knowing that the roots which emerge from the buried stem will help the plant grow more vigorously .
Tomatoes may also form roots along the stem aboveground when humidity is high. Sometimes it is in reaction to stress or disease. Some varieties are more likely to do it than others. The adventitious roots you observe might be there because your tomatoes are drought-stressed in their containers. It might also be in reaction to a common leaf disease, called early blight, which causes yellow leaves.
Consider spraying your tomato with a garden fungicide labeled for use on vegetables to control the leaf disease. Also think about the size of your containers: anything less that a 24 inch wide pot is too small to support happy tomato plants.