Vinca major spots
We think this looks like damage from the fourlined plant bug, a sucking insect. In large infestations the spots coalesce and turn brown. Most likely, the damage is done and many plants outgrow this damage by mid summer. You can prune damaged foliage. Keep the plants well watered.
Monitor the growth of the plants and send us more photos if you notice additional symptoms. We do not know where the barrels are located - sun/shade, how large they are, how they are cared for, etc. If you give us more information, we can offer some suggestions.
Hi, thanks for your answer. I am located in Henniker New Hampshire. I am a former Master Gardener from Montgomery County MD and have come to know that the UMD program is far superior to that of UNH, so this is why I reached back to you all. I will try to get a few more pictures. The barrel is located in mostly sun, and it has been excruciatingly hot and dry, and windy, here for the last month. We water the barrels 5 gallons every other day. They are whiskey keg style, with cocoa/coir sheets, moisture retaining pellets and new soil this year. They are otherwise going gangbusters, except for something eating holes in the potato vine leaves which I'm not as worried about. The vinca (which is a bad choice in material, but not by me) has this pest. Thanks again, I miss the MD MGs sooooo much!
All you can do for the vinca is prune back the damaged foliage to healthy tissue. The plants should put out new growth and monitor for additional symptoms.
Also, the holes in the potato vine foliage may have been made by a leaf feeding beetle, a tortoise beetle. They can chew small holes in sweet potato vine and morning glory. No control is necessary.
You are located in a state that has a much shorter growing season than ours. At this point it would be helpful to contact some of your local garden centers or nurseries to see what grows well in containers in your area.