Whiteflies?

Please post a picture or 2.

Jane,

Attaching 2 photos of the white powdery thing found under the tomoto leaves. Please suggesta remedy to eradicate this

Those are whiteflies laying eggs under your leaves. Whiteflies is my worst enemy, you need to get rid of them quick. They carry a disease called tomato yellow leaf curl virus. Once the plant is infected it may take up to 2 weeks to show symptom and then the plant is permanently stunted, you will not get any reasonable production out of them, even so the fruits won't taste good.

My neighborhood was infested with it and it can be hard to get rid until I make changes to whole garden. I had to pull all plants they like to host on, nightshade plants (tomato, pepper, potatoes). They like laying eggs under banana leaves as well. They like warmth, calmness, shade, and humidity. They generally come around during damp weather, so good sun exposure and windy deter them a bit. I tried growing companion plants and they aren't even afraid of them, landing next to the rosemary. I apply cold pressed neem oil (not the cheap neem bought from Home Depot which is not effective) and pepper mint soap under all the leaves of all plants that they like to host on. I pretty much check for all traces of them under leaves and use my garden hose to spray the underside of all the plants. On dry days I also apply diatomaceous earth to the bottom of leaves which makes it harder for them to nest on.

It's a constant battle of cleaning up the shades in the garden and routinely spraying to kill the eggs and disrupt their breeding cycle so you can slowly reduce their population. Fortunately they do not like cold so during winter most of them seems to go away. I couldn't grow tomatoes for an entire summer because of them, I make sure to not make the same mistake next summer and concentrate on growing other crops they aren't attracted to.

If they are whiteflies -- I'm not certain about that -- it doesn't guarantee that they carry virus.

It's whiteflies, very clear to see, there is no argument here. It may not guarantee they carry the virus, but you won't want to risk it if you know what damages yellow leaf virus can do.

Here in the tropics we have all sorts of poisonous plants that can be readily used to literally kil the bugs right away. Prevention may be best, planting tomatoes with aromatic herbs, and also spraying natural insect repellents such as garlic sprays, tobaco, etc... if you want to learn about it there´s plenty info on plants that grow in your área that could serve the purpose to control insect pests... if they fly no doubt they´re White flies, but I hope you don´t have cottony scales too....