My Yukon Golds (store bought) grown in half whiskey barrel did
wonderfully through the spring. In the last week though leaves at the
bottom began curling up and now most of the plant's leaves are curled

Some of the earlier curling leaves now show signs of dryness around
the edges and tip. also some very faint red or light, very tiny
spotting on the underside (which, in some cases, bleeds through to the
upper side)

Is this a bacterial/fungal wilt? too much water? -- the barrel drains
well. i can't believe its drought. no evidence of mold anywhere.

thanks, Bryan