Southern Blight: An Invasive Tomato Disease

There are many different diseases and conditions that can harm your tomato plant and some of them are very invasive. Diseases that harm a tomato plant can end up killing the plant all together or it could invade the soil infecting other crops. A tomato plant is very fragile and you need to take care of it to ensure that a devastating disease does not occur. If you have a tomato plant then you need to check out the various diseases that can occur and learn how to prevent them from happening. One of the most devastating and intrusive tomato diseases you can get is the southern blight. Southern blight can wreck your tomato plant and make replanting impossible.

Southern blight is a condition that can infect a tomato and can present itself in two ways which are white mold and stem rot. Southern blight is caused from a soil-borne fungus and it is common on a lot of vegetables and fruits but is mostly seen on tomatoes. A tomato can be affected with southern blight at any stage and it is usually caused by environmental conditions. Environmental conditions such as moisture and high temperatures are often seen in a tomato plant suffering from southern blight. A tomato with southern blight will often show signs if it is infected and will show various symptoms.

The first symptoms of southern blight will often appear in the tomato while it is above the ground and consist of yellow leaves and wilting. The stem which is near the soil will look sunken and will feel very soft to the touch. The stem will also develop brown and black sports on the inside and outside as well. If you live in a moist environment then the tomato will have a white fungus growing on it near the lower stem. The white fungal growth can also be seen on the tomato if it is in contact with the soil and it will show up on crop debris surrounding the soil. If you think your tomato plant is infected with southern blight then there is a simple test you can do. Simply place a part of the lower stem in a paper towel that is wet and then place it inside a closed plastic bag. Keep it in there for 24 hours and then see if the white fungus develops, and if it does then you know your tomato plant has southern blight.

The southern blight fungus can spread in infested organic matter or it can be infested in the soil itself. The soil surface is usually where the infestation of the southern blight will occur but it can also occur underneath the soil. Southern blight fungus is very invasive and can actually spread three feet through the soil which makes other plants susceptible to this disease. A whole row of tomato plants can be killed within a matter of a few days if the fungus ends up spreading throughout the soil. The tomato plants will die and the next crop will be severely infested with southern blight as well. It is hard to control the spread of southern blight once it starts because it is so invasive and spreads very quickly in the soil. If you live in a warm or moist environment then it will make it that much harder to control the southern blight. The best thing to do to stop southern blight from taking over your tomato plant is to prevent it in the first place.

If you have tomato plants then you should rotate it with other crops such as cotton or corn to help stop the disease from infesting the tomato plants. You also want to make sure that you do not plant the tomato plant in the same location more than once in five years to ensure the soil is safe and not infested with southern blight. Plowing the soil very deep can also stop the infestation of southern blight and it can bury the old tomato plant debris. Planting your tomatoes further apart can also help stop southern blight from occurring because the plant will be getting more air and ventilation which can stop the moist environmental conditions. The planting of the tomatoes further apart can also help an infected tomato plant and will keep it from spreading to other plants and invading the soil. If you really want to make sure that southern blight does not take over, you can fumigate your soil which can stop the disease from spreading. Soil fumigation will not rid the soil of the southern blight but it can help control the disease and make it harder for it to spread through the soil.

Alabama Cooperative Extension System, "Wilt Diseases of Tomatoes", Alabama A&M University and Auburn University