This prevents crowding fruit between the stem and the stake. Plants pruned to a single stem develop all flower clusters on the same side of the stem. Tomatoes are susceptible to a wide range of foliar diseases. Protect the plants with preventive fungicide sprays. Spray applications made after the diseases are widespread help to bring the disease under control but do not repair damage already done or replace leaves already lost to disease.
Some gardeners are reluctant to apply fungicide unless rain has occurred since the last application.
Keep in mind that heat and light destroy these chemicals and the plants are constantly adding new growth. So, frequent applications of fungicides are needed at all times. Insecticides may be added to fungicide sprays when needed to control specific insect problems. Malathion at the label rate will control aphids. Sevin will control stink bugs and small fruit worms, and diazinon and Cygon may give limited control of leaf miners and whiteflies.