Question
I have what appears to be a fungus in my garden soil that is killing my tomato and zucchini plants. When I loosen the soil around the plants, I dig up small white irregular shaped pieces of something that feel like rubber. Any ideas?

Answer
There is a fungal disease called southern blight that affects many garden veggies.  The fungus attacks the plant at the soil line causing a crown rot which cuts off the water flow in the plant followed by a fast wilting and death.  The fungus can be observed on the stem of the plant and on the soil surface.  Affected plants need to be pulled up and destroyed away from the garden as the fungus makes a survival spore that will hang around in the soil for years.  For healthy plants, you can mix up a drench of a fungicide called Daconil.  Two ounces in a gallon of water and pour about a cupful around the base of each plant.  This will help prevent the fungus from growing towards the plant.  If possible, move those type of plants to another place in the garden next year.  Planting corn in that spot will help reduce the number of surviving spores, since it is a non-host. I hope this helps.  Good Luck.