where are you located?
could you show us a picture?
In the long run, the key to keeping pests in balance so they don't do too much damage to your crops is to work on making your backyard a balanced ecosystem. Whiteflies are controlled by lacewings, ladybugs, hoverflies and other insects and small birds, etc. So you want to invite these things in to your garden. Have bird baths and bird feeders. Have lots of flowers of the type that the beneficial insects like. This would be things like yarrow, all the carrot family stuff if allowed to flower (dill, fennel, parsley, coriander, caraway, etc), tansy, buckwheat, sunflower, alyssum, cosmos, marigold, lemon balm, zinnias, thyme, etc.
In the short run, you could try Neem oil.