Darn i think it is late blight. I will remove the infected row today do you think the rest will be infected also? No way to stop it huh?

I suspect the soil in that very shallow box is just heating up too much and stressing the roots. That would account for yellowing and drying of the lower foliage for sure. Potatoes are not necessarily considered deeply rooted plants but most sources will indicate that they need at least a 12-18" soil depth. Plus the mounding of soil one does to increase tuber production along the stems. I would personally never attempt to grow taters in such a shallow bed/box........nor would I consider any other veggies appropriate for that depth other than salad greens or maybe French radishes except for on a very temporary (i.e., seed startling) basis. YMMV

For the past 5 years I've only grown Yukon golds too and like them but tried Kennebeck this season with so-so results, Haven't eaten KBs yet as we just dug them a week ago. Please post your final results on the BGs. I like YGs but when they get to be baker size they can get hollow heart or a weird gap/space in the center.

I can see were EG would not work here. A darker, warmer gray might but I would keep it simple myself. I think your cabinets are lovely. It’s very hard to tell how any color will look in a space viewing it on a monitor! Nearly impossible actually. This is just a suggestion. You could try a neutral, lighter color such as BM barely beige. It still has warmth but isn’t yellow. Here it is compared to your current color. See how it looks with your trim though, you may have to repaint that. You could do the trim in the same color in a higher sheen.