White or yellow patches on green fruit is sunscald. This happens with sudden exposure to hot, dry, sunny days. Try to keep the tomatoes somewhat shaded by their own leaves. Several different insects and diseases bother tomatoes. Control these problems by using approved insecticides and fungicides.
Common problems are on the next page.
Or, ask your county Extension agent or reputable garden center staff what to use to control tomato insects and diseases. Follow the directions on the container. If you run into more than the above, see our Plant Problems series for more information. Harvesting Pick tomatoes at full color for best quality. If you pick them when they are pink, let them ripen at room temperature.