Just flushing them off plants, like Aphids, is a good control measure and while Insecticidal Soap sprays may help they also might kill some of the beneficials that could help control these pests.
Some sources are now suggesting using a systemic, like Imidicloprid, but there is some indication this poison kills the pollinators.

Here is a link that might be useful: About Whitefly

in the last few weeks my veg have stopped growing and the leaves all dying.

==>>>\

first.. i see fruit there ... they are transitioning from leave growing to flesh growing .... plus they are still flowering ... a bit too much drama i think ...

second ..... the leaves are partially damaged.. but any green is still doing the job ... and i dont see that they are ALL dying ...

i am thinking.. you are in the mid summer doldrums .... and they are changing their growth patterns.. and you are panicking ...

observe.. react.. but dont panic ... it kinda defeats the whole idea of relaxing while playing in the dirt ...

ken

Whitefly does not do that type of damage, as what the photo indicates. They are a sucking, not a rasping insect.

The tan-colored tissue died because of a water shortage, even though it may have been brief.

Edit to add:

It appears you're using drip irrigation. I'd bet money that you're not running the system long enough and/or you have insufficient drippers.

To verify, check the soil moisture content -- stick a finger in ti -- to determine where it's wet/moist and where dry.