Tomatoes are vulnerable to a variety of different diseases and infestations. Some common tomato ailments cause the upper leaves of the plant to shrivel up. The symptoms associated with the shrivelling can help you identify the problem your plants are suffering from.
Curly top is a viral infection that is passed along by the beet leafhopper. It causes the upper leaves to roll up and turn purplish. The rest of the plant turns yellow and stops growing.
Late blight sometimes presents itself just in the upper leaves at first. It gives the leaves irregular greenish-black blotches that rapidly grow in size. A fuzzy white growth sometimes occurs on the undersides of the leaves. This infection can lead to rotting fruit.
The earliest stages of bacterial canker manifest as a wilting and shrivelling of the youngest leaves at the top of the plant. This usually occurs only on one side of the plant. Though the leaves shrivel, they remain attached to the stem.