Tomato plants with wilted yellow, brown leaves may have a blight. It usually starts from the bottom up. In order to control this you should remove the infected leaves. You could spray your tomatoes with Later’s copper or other appropriate fungicide. Next spring you should also solarize your soil. To do this you must cover the soil with clear plastic, making sure that the soil is moist. Leave the plastic for a few days, during which the sun’s rays will have pasteurized the soil. You should plant VFN varieties which are resistant to some tomato pathogens. When watering try to minimize the amount of water and soil splashed onto the plant. mulching around the plants will also help.
Tomato plants which show no symptoms of yellowing but the leaves are curled, mainly at the top, may have been affected by 2,4-D herbicide which can drift long distances in the air. Depending on the air currents, it can may effect only a few plants, or many.
Compiled by: Dr. Bill Paton and Vicki East