i would think it's the cold, assuming it's uniform yellowing; temps have been below 50 degrees at night regularly, and we've have two freezes in the last month. have you ever grown in this spot before? did you have problems then?

if leaves are wilting on random branches (but staying green) it's probably a wilt, like verticillium wilt. not something you want.

I've never grown in this spot before- it's a new house. But the neighbors says he grows beautiful tomatoes right next to that spot. So I don't think there are any fungal diseases that overwintered.

The yellowing is pretty uniform- the veins don't seem to be greener or yellower than the rest of the leaf, and it's all over the plant. Let's hope it's the cold and that my plant will perk up when it gets warmer. If not, oh well- I'll just have to plant more seedlings to take its place!

We think of tomatoes as annuals, but really they are tropical plants that dislike temperatures below 50 degrees. I think your yellowing is cold nights.

The ones I put out early are a bit on the yellow side as well. They're perking up nicely these last few days. I'd give them some time, don't water them for a while (that can yellow leaves as well) since we've had so much rain and it's supposed to rain again soon and see how they do.

Here is a link that might be useful: The Corner Yard

Yes i think it is the temperatures as well. I have over a thousand planted and they all did that at two separate plots.since we have been in the 80s my plants are off like a rocket.

I have rather bright yellowing on new tomato plants, planted in earth box one week ago. It is in the approximate center of the plant. Being in an earth box with new soil and fertilizer I don't think the cause is water or nutrient. I have treated with fungicide. This is the first time I've encountered this problem. Any ideas?

I simply remove the yellow leaves.