Every year I get something that looks like black spot on my tomatoes but after reading several articles on the internet I think it's septoria. My plants get brown or black spots on the leaves, it starts at the bottom and works it's way up, eventually the leaves turn brown completely and fall off. The fruit is not affected by this. Several articles suggest not planting them in the same spot every year but I do container gardening and that's all I grow so there isn't another spot to plant them in. What else can I do?
Jackson County Michigan tomatoes
Thank you for your question. I am sorry it has taken a while to get you an answer. While disease on your tomato plant's leaves appears to be septoria, tomatoes are subject to a host of plant problems, which you can read about here: http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomLeaf/TomLeafKey.html
Here is an MSU article on septoria, specifically, (that you might have already read): http://www.canr.msu.edu/news/septoria_leaf_spot_of_tomatoes
The best way to prevent it from occurring year after year if growing them in containers is to change out the potting soil every year, and disinfect the pots, as recommended in this Extension article for greenhouses: https://ag.umass.edu/greenhouse-floriculture/fact-sheets/cleaning-disinfecting-greenhouse
However, if the containers you are using (I cannot see from the photos) are of absorbent material (such as wood and some plastics), this is more difficult. But if you start in the fall after removing all soil and other organic material such as leaves, stems and fruit, you stand a better chance of preventing its repetition in the spring. Hope this is helpful. Good luck!
Sorry about the delay, seems there was a technical problem.
Here are some other things to consider. Septoria lycopesici can also be found on plant supports, garden tools, and nearby solanaceous weeds. Seeds can also carry the disease. Insect can spread it. This disease can be spread by water splashing from the soil onto the leaves. Be careful when watering. Removing lower leaves can be beneficial. Make sure you don’t transfer the disease from plant to plant when pruning and be sure to disinfect your tools between cuts (alcohol works). Don't work on plants when wet. Check out the following link: https://ag.umass.edu/vegetable/fact-sheets/solanaceous-septoria-leaf-spot
I hope this is helpful,
Thank you so much! I will be trying everyone's suggestion and look forward to, hopefully, a disease free growing season next year.