I have four tomato plants in containers, two are having problems with leaves near the bottom turning yellow and dying, one still has new growth occurring near the top but the other one has stopped growing new leaves and the leaves at the top half are small. Other than that the plants look pretty healthy, at least to my untrained eye.

But every day there are more yellow leaves at the bottom and as I remove them the foliage is really starting to thin out.

I had a bit of an aphid problem but in the last week a bunch of ladybug eggs have hatched and the plants are swarming with ladybug larvae so the aphids are vanishing pretty quickly.

The tomatoes are in containers in a Raybo 3-2-1 mix.

Does anyone have any idea what is killing them and if/how I can stop it?