For environmental context, I live in Charleston, South Carolina. Our temperatures have been between 70-85F during the day, and around 60-75F at night.

Of the 3 you list it is iron deficiency that would affect the color but I would first look to your nitrogen. Those fertilizer spikes are not nearly as long lasting as you may think, especially in containers that are heavily watered, and are not sufficient over the long term. Heavily watered containers often need regular weekly feeding.

Dave

If it's not a mineral deficiency, I believe the disease in question would be Tomato Yellow Leaf Curl Virus rather than Curly Top Virus.

AVRDC -- World Vegetable Center

University of Hawaii

UC Davis

I see some leaflet cupping in polyfractal's photos, but I don't see the stunted, shortened leaflets from the TYLCV photos. That might mean polyfractal's tomato doesn't have TYLCV. But of course I'm not an expert.

[I thought I remembered polyfractal saying he was downstate in North Carolina, and found a 2002 report of Tomato Yellow Leaf Curl Virus in Henderson County (NC), where they do grow a lot of commercial tomatoes. That's a bit too close for comfort! Nematodes in Polk County, too. WNC is just chock-full of tomato peril.]

Thanks Missing, It is TYLCV I was thinking of. Never had it just heard about it around these forums and have seen the pix.

I would like to add a quick note: In general, tomato viruses are fairly rare and generally need insects to spread them from somewhere nearby.

That being said, container plant nutrient deficiencies are very common - unless you choose to do a closed system like earth-tainers, etc.

More than likely, adding a good water-soluble balanced fertilizer (one with micro-nutrients) will clear up the issue. You could also add a little epsom salts during one of your subsequent waterings - and that would more than likely help things along.

If it is a virus (which I'm fairly skeptical of) then there's really nothing you can do other than to toss the plant. If it's not, then adding nutrients will fix the issue.

Thanks for the responses everyone! I'll start treating it as an overwatering/nutrient deficiency problem and see if that clears up the problem.

I didn't realize that fertilizer spikes depleted so quickly in containers. That could very well be my problem. I'll start supplementing with some soluble fertilizer w/ micronutrients.

I'm pretty sure it isn't a lack of nitrogen since there are a lot of lower (older) leaves that are remaining robust and dark green. If I understand correctly, nitrogen will be translocated to higher leaves when there is a deficiency, so all lower leaves will yellow, not just the youngest.

Here's to hoping it isn't a virus :) Thanks again!

nitrogen since there are a lot of lower (older) leaves that are remaining robust and dark green.

True but N deficiency shows up in NEW growth, not old growth. Yellowing of old growth is almost always over-watering.

Dave

Oooh, ok, that makes sense. Thanks for the clarification. The tomato spikes are really low in nitrogen too, so combined with being used faster than I expected maybe my plants are just starved of nitrogen.