Tomato Problems

Question: This year I decided to grow my own heirloom tomatoes because they are so expensive in the store but the lower leaves are dying and the problem is moving up the plant. Can you tell me what is going on and how can I stop the plant from dying? Also, I have heard a lot about tomatoes and salmonella lately – should I be concerned about my garden tomatoes?

Answer: Now you know why heirloom tomatoes are so expensive. Most of them have little or no disease resistance and they tend to make a lot of foliage compared to the amount of fruit produced. This is another reason for their expense plus a possible reason for increased disease. The large amount of foliage means the foliage stays wet longer after rain and dew. Wet foliage means increased foliar diseases like “early blight” which is the likely culprit on your plants. The relatively cool wet weather earlier this spring made for perfect conditions to spread early blight. Click here for other disease possibilites: http://www.aces.edu/pubs/docs/A/ANR-0895/

Early blight is the most common and widespread foliar disease on tomatoes in the southeast. If not controlled, this disease can severely damage fruit quality and lower yields. On young plants, dark brown, irregular spots form and completely encircle the stem, causing plants to quickly wither and die. On older plants like yours, the spots are restricted to one side of the stem. Leaf spots, which typically occur first on older leaves, begin as small (1/l6 to 1/8 inch in diameter), dark, irregular spots and enlarge to form larger spots up to ½ inch in diameter. Tissue surrounding these spots often will turn yellow, resulting in early defoliation. On severely infected plants, fruit may become sunscalded because of the lack of foliage for protection.
Once the disease becomes severe on individual plants control is unlikely. Removing infected leaves from the garden can help. Other cultural controls for this disease include; mulch to prevent soil splashing onto lower leaves, proper fertilization, don’t wet the foliage when watering, stake or cage the plants and prune off side shoots. Fungicides are also available and do a good job preventing disease but they don’t cure disease.
Let me elaborate on a couple of the cultural control options. Nitrogen fertilizer is a good thing for plants like tomatoes that grow fast but excessive fertility leads to growth that is often more susceptible to pest. There is a fine line between enough and too much fertilizer. If your plants are dark green and growing very fast you may have crossed the line. Along a related path you might want to prune excess growth off by removing side shoots called suckers. These suckers grow from the main shoot at an angle from leaf attachment points. In general they are less fruitful and the thick growth that results is more prone to disease because it is vigorous and causes the plant to dry slower after a rain or dew.
I have a couple thoughts about your salmonella question. First, salmonella is not a disease that tomatoes can contract but a contamination that can happen during harvest and/or packing. Second, it is possible to have salmonella contaminate even your garden tomatoes. As a precaution you should never apply fresh animal manure to the soil surface when vegetables are in the garden. Always compost animal manures well or till them into the soil before planting. Consider using a mulch around plants to reduce the risk of animal fecal matter splashing onto tomato fruit and other vegetables. Tomatoes that are home grown or vine ripened locally are very unlikely to pose a serious health risk. Nevertheless, even your own garden vegetables should be handled with clean hands and washed thoroughly before eating. You should take the same precautions you expect your favorite restaurants chef to take when handling vegetables to be eaten raw.