I have a 40' long row of raspberries that have dragged their feet over the years. Recently I was told to check the ph of the soil. I just bought a ph meter and measured 7.5 to 8 ph across the row. I understand that raspberries like the soil ph to be 5.5 to 6.5. What's the best method to lower the ph of my soil here?

Thanks in advance - Mike

Use Epsoma soil acidifier and Epsoma Berry Tone. Just follow the instructions. You would not want to try to drop the pH all the way this year as the concentrations are too much creating a bad layer for a while. Consider a program of 2x per year, One early and one later after berries are gone.

You always want to make changes slowly so you don't shock your plants. Don't try to get from 8 to 6.5 all at once, slow and steady is the way to go. Use recommended fertilizers, but if it were me I would dose half as much 2x as often. Most plants will learn to live with less than ideal conditions, but struggle to handle rapid changes, especially when active growing, so start now.

Where are you located? I'm trying to figure out how it got that high and what you have around you so you can lower it and keep it lower overtime without buying extra stuff.
If you have hard water and water often, that will increase alkalinity, so collecting rainwater is a great way to avoid that. Even if you have a well, allowing the water to seep through the soil will dissolve ions.. collect it right from your gutters.
Mulching with oak leaves (grind them up with the lawnmower first) is another fabulous way to increase acidity over time. And it will also keep down weeds. If you have evergreen pine trees, rake up the detritus under them and place it around the base of your berries to get faster results.

If, like me, you have the opposite problem, soil too acidic, oak is still the answer, you just have to burn it first, lol. Hardwood fireplace ash can be used instead of lawn lime at a 2:1 ratio.

Almost forgot! Do you drink coffee? Coffee grounds are extremely acidic and make GREAT compost for alkaline soil. If you drink coffee like I do, by the time spring comes around you wouldn't need to buy anything else!