I haven't done much spraying yet. Only dormant spray I have worked with so far is Liqui-Cop. When I asked the guy what sprayer to use with it, I expected him to show me to one of those backpack sprayers, or maybe one of those tall cylinders with the pump on top. Instead, he sold me an attachment for the end of the hose. You just pour the Liqui-Cop in the hopper and set the mix ratio and spray down the trees. I have used pump sprayers for spraying compost tea and beneficial microbes. I have always had problems with the pump blowing a seal, the tip getting clogged, or just the chore of pumping. The hose sprayer was much easier to use.

I just used a cheapo one gallon pump when I had a few trees. Lowes special.