The leaves at the bottom of my tomato plants are turning yellow and seem to be moving up the plants. What is the problem?
The Gardener’s Answer
Hello, Lillian: This seems to be a common problem with many gardeners this year. The amount of rainfall we have had this year has a direct effect on the potential problem. The most likely cause of the foliage turning yellow is a type of fungal disease such as early or late blight. Good sanitation and fertilization will help prevent spread. Remove and dispose of all foliage that is not healthy. This disease starts on the lower leaves and then works its way up the plant. The fungal spores can be splashed up onto the foliage during rainfall or hand watering, so adding a thin layer of mulch around the plants will help prevent the fungus from spreading. Maintaining proper fertility and good drainage is also important in terms of growing a healthy crop. Nitrogen deficiency is a common problem with tomatoes and has some of the same symptoms. Solving this problem is as easy as spraying the foliage with a general purpose fertilizer such as fish emulsion; this will give your plants instant nutrients. Then apply a slow-release granular fertilizer to maintain a healthy nutrient level. Make sure your tomatoes are planted in full sun and have good air circulation. They are more susceptible to disease when they do not receive sufficient sunlight or are over-crowded.