We use soap if needed. Really only on brassicaes (collards seem to be the worst). We don’t worry too much about leftover spots though, they should all come off during the washing of the produce. We also have not done regular foliar sprays in previous seasons, but will be starting a more regular regimen this season so I am interested in what people are using as we may see this become a bigger issue for us this season.

Also one thing to consider is the spray nozzle and the resulting droplet size. You often don’t want to apply things to a stage where the product is dripping off the plant.