Sally writes~ I have a problem my tomato leaves are curling really tight. They did this once before only one plant and then is was OK, but this year they are all doing it. Please tell me what to do.
A. Leaf curl is common. Almost all modern hybrids have leaves that curl, so do some heirlooms. Leaves also can curl if it is too hot, too cold, too dry, too wet or there is a heavy fruit burden. Leaf curl is to be distinguished from leaf roll, a common condition seen early in the season when root and foliage ratios are out of whack. As the plants mature this goes away.
What comes to my mind what curls and kills the leave of tomato plants is a tobacco virus. Is there someone who uses tobacco products touching the plants or even getting close to them? Is someone growing tobacco in your neighborhood? Tomato plants are terribly susceptible to tobacco and nicotine and their viruses.
When you purchase tomatoes, whether it be transplants or seeds, get the kind with the most virus and disease resistance, the tags will refer to VF and VFN resistance on the name label. These varieties have been developed with natural disease resistance, and it sure does work. In very high humidity, tomatoes can often get the viruses without the natural resistance type.
Do you actively 'de-sucker' your plants? Only do this once or twice at the beginning of the season and then leave them alone. I had a leaf curl problem similar to what you are describing when I would sucker them heavily. The plants would eventually recover.
Here is a great UC Davis website for the pests and diseases of tomatoes:
http://axp.ipm.ucdavis.edu/PMG/selectnewpest.tomatoes.html Source