Question
The top leaves are curling up on my tomato plants.  Any idea why?  The rest of the plants look OK.

Answer
Dear Richard, There are basically two things that could be causing this.  One of these is fusarium wilt.  This disease usually affects the older heirloom varieties of tomato.  Often these days when you buy a tomato plant, it will come with letters after the name, V, F, or VF, and I think there are a couple of other letters.  Anyway, the F stands for Fusarium wilt resistant, so those plants will be more resistant to this condition.  However, if you do have fusarium wilt, the plant will likely wilt and be completely down within a few days.  In addition when you slice into the plant you will see black plugs in the plant tissue.  These plugs block the flow of water to the plant, thereby giving it the plant equivalent of a heart attack.  Probably what is wrong with your plant is lack of sufficient water.  Tomatoes require a huge amount of water, probably why I'm not growing any this year.  They will wilt very quickly in high temperatures.  Increase the water amount, and cut off any long, low growing suckers, and your plant should perk up.  If the cause is indeed the wilt, you will know by the time you see this post.  In that case, I would remove the plant, dispose of it carefully, and I would probably plant another kind of vegetable in that spot for this year.  I hope this information helps.  Good luck, Melissa