Appears to be Successful

I thoroughly checked over the 2 tomato plants that I bought from the nursery. I planted them and then noticed that one of the plants was struggling. The leaves were browning, curling and dying. Could the plant have picked up a disease from the soil? Or was it diseased to begin with? I decided that I would cut the browning parts off the leaves. It might kill the plant, but then the tomato plant was going to die anyway if I did nothing. For now the surgery is successful. The leaves are healthy and both plants have blossoms. This is not to say however that the plants are not targets for insects, hail, high winds and other disasters.