I don't think it could be a caterpillar as there is no soil in my basement, and I am growing with aeroponics. Here are some more details and pictures.

I am growing using aeroponics (low pressure). The plants are wilting from the bottom branches upwards. As each branch wilts and dies the next one up does the same. The leaves are also curling downards and curling in on themselves. The bottom most leaves are tough and leathery and have purple and yellow color. The main stem is purple near the bottom. The person at the hydroponics shop said that he believes my nutrient tank is getting too cold. I checked the temperature and its 70F during the day. I know the air temperature under the 400W HPS lamp remains around 74F during the day, but goes to about 64F at night. Lowest nightime air temperature in the last 30 days was 61F. I am uncertain what the temperature of the water (nutrients) goes down to at night time. I am growing these in my basement and the nutrient tank is sitting on the cold concrete floor of my basement. I have tried two different fertilizers and have grown the same tomatoes in deep water culture without issue using the same fertilizer. I have tried adding hydrogen perioxide to the nutrient water but it did not help. The roots are white and look healthly although the number of roots seems to be stunted as I would expect more roots after 30 days of growing than I am seeing. I have tried regrowing the same tomato plants several times and each time I have cleaned my system out completely, yet I still end up with the same issue. The only thing I can think of us that the water is getting too cold at night. I have my aeroponic sprayers running 1 minute on and 5 minutes off, 24/7. My 400W HPS lamp runs 16 hours on, 8 hours off each day. Running about 700PPM right now, ph is around 6.3. I have tried higher and lower nutrient levels and higher and lower ph levels which did not appear to help.

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Have you had any luck figuring this out bionicman? Your plants look exactly like mine. The top is fairly healthy but the bottom leaves start to curl and dry up.

The leaves on the lower branches my tomato plants are turning under and drying up. The pH is 6.2. The solution reads 2.9. The medium is coir.
The nutrients are Ionic Grow and Ionic Bloom. I am using a 6 unit Autopot system. My tomato fruit are growing however. Why are the lower leaves drying up and turning under?

bmahon,

I "think" I figured this out. I believe it was being caused by the fact that I was growing my plants in a tan colored rubbermaid containing. Because the system is a low pressure aeroponics setup without any medium, the light was bleeding through the sides of the container and hitting the roots. I don't think the roots liked it. I wrapped the entire container with black and white poly to block out all light and all of a sudden the roots started growing laterally and the plants have started uncurling. I did the same with my pepper plants and strawberry plants and noticed that the fruit yield on them increased within a few days. I was also getting calcium deficiency on my strawberries and when I blocked out the light it all went away. So I think that was the cause of the issue, but I will probably have a better idea in a week.

Bionicman, hi.

this post is already a few years old, but i was wondering how you solved the issue, as i am experiencing exactly the same symtoms on my plants.

thanks for you help.
Pl4nB