Hi! Thanks for your reply.

I guess they did not receive enough sunlight. Also, I do provide additional fertilizer other than just rice water to them, and nothing else. Is there anything I should add?

The white stuff under the leaves are moldy powder like, and when I use my fingers to remove them, it appears that there are some black dots at the back of it, not sure what it is.

I've now moved them to an area with more sunlight.

On the other hand, what should I do with the leaf miners? Do I just cut off the infected leaves?

Your plant needs to keep all the green parts possible. When you see the very first indication that a leafminer is beginning a new trail, squish it while still inside the leaf.

If you wait, they drop into the soil (potting mix) and will soon be adults which can lay more eggs.

The white stuff are whiteflies and their eggs, we have an infestation problem with them in South Florida. Whiteflies are from the tropics and can carry a disease called tomato yellow leaf curl virus. Leafhoppers also carries it. Once your plant is infected with leaf curl virus, the plant will almost stop growing and not produce anything, there is no cure. I'm not saying whiteflies definitely carry the virus, they may not, but it is something I've very wary of. I was not able to grow tomatoes for the most of 2015 because of them.

Whiteflies like warm temperature so there are much less of them during the cooler months. They prefer shade, warmth, and protection from wind. They are attracted to nightshade plants, the virus infect nightshade plants such as tomato, pepper, goji, potato, basil. But they are attracted to a wider variety of plants while not infecting them, like the "bidens" plants (common lawn "weed"), brassica crops, banana and other type of leaves that may provide good shades.

This season growing tomatoes in spring with the cooler temperature I have less problem with them. Also with mulching and keeping the plants healthy reduces my pests issues. I notice whiteflies like to attack the lower sick leaves, so I pruned them and maintain a good airflow in the bottom.

It seems as if your tomatoes are badly infected, not only by one pest, but several. The first plant is badly taken up by Leafminers. I drew that conclusion as a consequence of the patterns and object seen in the leaves of the plant. The infestation seems pretty bad but you can try a combination of methods to get rid of the infestation. If your tomatoes are very healthy, they will survive, but if not, growth will be hindered. You could try pruning or remove the leaves that are infested, or given the look of the infestation, you might have to do an overall procedure. I'm talking about pruning, insecticides or parasitic wasps (do not use both as the insecticides could kill the wasps). As for the whiteflies, you can use the link attached to this comment as a reference. All the best. http://goo.gl/7DSRXl

I just cut the leaves off of my tomatoes that have the leaf miners. I never had luck finding them in order to squish them.

An organic pesticide called Spinsodad wreaks havoc on leaf miners.Ladybugs will

gorge on whiteflies. Neonicotinoids also kill whiteflies,but the also kill honeybees,

which could reduce your tomato crop,as their will be less pollinators.

I've got rid of those leafminers by pruning those parts that they're in, but there's still a lot of whiteflies. And maxjohnson, the whiteflies are just getting more and more. Besides, some of the branches with leaves are also curled up, which I guess it's the tomato yellow leaf curl virus. What should I do? As not all the leaves are curled, can it be helped by trimming those curled leaves? Besides, my tomato plant is still growing and still producing fruit, and I'm pretty confused right now.