Our tomatoes were doing great; thick strong stems, dark green leaves, flowers blooming, fruit forming.... then one morning about a week ago I walked into the garden to find some of them wilting. Oh, crap, the dreaded southern blight is back! This is some evil stuff for which there is no organic remedy. It is a soil borne fungus that attacks the stem of the plant at the soil line. By the time you see the symptoms ( leaf yellowing and wilting of the stems) it is usually too late to do anything.
But I had to try. I do not want to lose my whole tomato crop in the front garden. The first thing I did was to treat the plants with Bacillus subtilis (Sererenade) a bacteria that attacks fungi. When I examined the plants to confirm my suspicions i noticed the presence of adventitious roots ( the little bumps) along the stem.
I thought that maybe i could make a kind of poultice out of worm castings by soaking them in water and packing them around the stem to provide a medium for the adventitious roots to grow into making a new root system above the dying one. I did that and one of the plants is beginning to recover. I can see new roots growing out into the worm castings. We are going to have temperatures in the mid 90's for the next 10 days so it will be a race to see if the plant can grow roots fast enough to meet its water needs in the heat.
The blight has spread to several neighboring plants. I placed poultices around them and pruned the wilted stems to reduce stress. Tomorrow I will put poultices around the rest of the plants in this part of the garden as a preventative measure. It is possible that there are beneficial organisms in the worm casting that will attack the blight and protect the remaining plants.
This stuff will attack beans, melons, peppers and many other plants. It will persist in the soil for several years. It will not survive being buried deep in the soil and it requires undecomposed organic matter to get started. Apparently grasses, i.e. rye or wheat, are not hosts so i will probably till deeply and plant a cover crop in the fall.
I will post updates about whether or not my palliative measures are working.
As a further precaution I got some replacement plants and planted them in a bed far away from the infected ones so I will have a later crop to take their places if this crap spreads.
Here is some additional information about Southern Blight from N.C. State extension. http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/vg9.htm