Hope this works!

Need to read the info about herbicide drift as well as potential contaminated organic matter.

full explanation at WSU, along with the bio-assay test to verify or not:
http://puyallup.wsu.edu/soilmgmt/Clopyralid.html

If the assay is positive, read the section that describes what you can plant and how you can speed breakdown of the herbicide.

Here is a link that might be useful: info re contaminated OM

Thanks, Jean. I guess the picture could make you think it is herbicide related as it isn't a good picture. But it is not. I have had 2,4-d damage in the past from contaminated manure and the leaves from that kind of damage are gnarled and leathery and deformed. The leaves on these plants are simply going limp, wilting and then dying. It is working its way up from the bottom of the plant. Affecting only Cherokee Purple and ARGG and none of my hybrids or dwarfs. All plants are in 15 gallon containers with good draining soiless mixture. (5-1-1). My co-workers are in the ground. She is baffled also. We have ruled out most of the systemic wilts and are thinking it just must be the tons and tons of rain we have gotten here in western NC.

Well since you are in NC, and are using a 511 mixture, are you sure they are getting enough water? I would imagine that a mature plant in the classic 511 mixture, with no additional peat added for water retention, would need a good soaking at least once per day. They might just be drying up in the sun and heat.

Ed,
You are be right! We have had record amounts of rain in June so I turned off the drip irrigation system. I didn't think this could possibly be related to not enough water. We have had storms almost everyday. But there must not have been enough rain. I went out this morning and stuck my finger in the soil and it was dry. I watered the plants and left for work. When I got home they had all perked up. It's my first year using containers and this was a lesson learned about the watering needs of containers versus in ground plants. Thanks Ed.