70 year old Grapes in Zone 8, Peloponnese, Greece, 960m, mildew

For the past years, we have had powdery mildew on our fruit grapes and rust on the leaves by July. Most of our neighbours tell us to do a sulfur fungicide...
We thought our pruning in autumn and spring helped the solution when the new grapes arrived but by July, the mildew returned. Perhaps from June rains.

Should we be pruning in May to thin out the growth?

The grape is in soil with a rosemary plant and yarrow and wild strawberry. It gets beautiful sunlight all day long.

We are really trying to preserve the beauty and production of these old vines with a permaculture approach, so asking advice on what more we can try. Have read this and want to reduce chemical residues as the grapes are in front of our house and under our outside dinner table.

https://www.novobac.com/powdery-mildew-of-grapes/ Any seasonal advice on how to prevent and resources to read will be a great help for us to come up with a plan.
Thank you Permies!

After I helped convince him of its benefits for my other garden plants, a viticulturist friend in the Willamette Valley in Oregon used primarily compost tea in getting a biodynamic vineyard he managed to produce 4x as much usable Chardonnay, when mildew was their primary problem. The owners complained that he made them work to sell so much more wine.

I would recommend making Johnson Su style for grapes as it is the best for beneficial fungi that will out compete and consume the mildew, as well as boost the plants’ natural defences.  As that method takes a year, I would buy the best fungally rich compost you can for the interim, looking for woody debris as its primary feed stock. Quality is key, but if its good compost it only takes about 2L to make a 200L batch for foliar spray. TeaLab has good recipes, but I would not add food to the brew for grapes. Rock dust and kelp can be helpful. If you cannot aerate, an extract will also help but may not stick to leaves as well. One spray on fallen leaves in autumn and then 3x+ in spring through early summer is a good regimen.

I have also had great success (95% reduction in mildew and nearly as much for botrytis) using horsetail (equisetum) tea. Either fill a bucket with the horsetail then top with water and wait 2 weeks. If urgent, boil a kettle of water, turn of heat, add horsetail to water line, and steep for 30min. Either brew method should be diluted at least 4:1 and up to 20:1, and sprayed on foliage top and bottom til dripping.

This YouTube gives several easily made solutions.   Possibly not going to eradicate, but certainly control.  Might help to reduce some of the canopy to allow  in light and air
Best of luck, it's a real pest.