I purchased ‘Dormanred’ raspberry plants from our local county extension office in 2014. They are trellised, have thrived, and are very generous producers, so no complaints there. HOWEVER, they do NOT have a traditional raspberry flavor, apparently because they are a hybrid with some other unknown more heat-tolerant bramble. I’ve gotten a lead on a test variety ‘Mandarin’ that was developed by NCSU back in the 50s that has a more traditional flavor and high heat-tolerance, but due to funding issues at the time was never commercially introduced. However, reportedly there ARE ‘Mandarin’ plants out there in private gardens. Does anyone know of this variety and have a lead on someone who actually grows it? Failing that, does anyone have a recommendation for a raspberry variety with a good flavor that can stand up to summer highs in the 90s?
My thoughts are that Charlotte is a bit brutal, but it’s not the hot days as much as it is the hot nights and the humidity that may cause grief.
I’ve grown things in the Charlotte area, but not raspberries. (Managed to get hemlock trees growing…for instance.)
I probably would check out a farmers market and see if anybody ever comes to market with raspberries…and get a feel from them if they can recommend any varieties that will do well there.
Great idea about the farmers markets. I’ll give that a try next summer. Thanks!
you are looking for a heat tolerant raspberry and I’m looking for cold tolerant blackberries. the struggle is real! 
Consider looking for a local U-pick or CSA operation. I’m not really that fond of reds so I’m not sure what mine grows.
I do know that if your summer temps reach the mid-upper 90s that blacks and yellows grow poorly and tend to sunburn if in full sun. I’m in Richmond in a 7a/b area, and leaf burn is a significant problem here.
I planted about 1/2 acre of raspberries in the 80’s using a variety suggested by a plant breeder at NCSU. The variety was Cherokee, introduced by VPI, which was an everbearing variety similar to Heritage. I bought tissue culture plants from Nourse
The suggestion was "clean plants, drip irrigation and 4 inches of straw mulch to help moderate soil temperature. The plants did great for about 3 years before starting to decline from the heat and disease. I did not try raspberries again.
I understand your frustration with Dormanred. Its not a traditional raspberry because one of the parents is some type of dewberry. It tastes more like a pineapple to me
Jim Ballington who located the old Mandarin plants has retired. You may be able to get your local extension agent to contact Gina Fernendez who is the bramble breeder at NCSU and see if she knows of a source of the plants.
Another good idea. Thanks.
Thanks for sharing the detailed background. Much appreciated.
I spent a lot of time and energy planting and tending to raspberries for about a decade in 7b before coming around to the realization that I could just go pick them in the wild with none of the work. They grow wild absolutely everywhere. Around me are several varieties of black raspberries, wineberries, even golden raspberries in two spots.
I visited the research farm in Reidsville, NC (about 30 miles away) and had a chance to see Mandarin and Cherokee growing along with others. Unfortunately, the tests proved that my area is not well suited for raspberries. The raspberry yields for all varieties tested in the piedmont region were only a fraction of the yields for the same varieties at the Fletcher research station in the mountains. Dr Ballington who was running the trials stopped by and took pictures of my Cherokee Raspberries several times. I thought my raspberries looked a lot better than those growing on the research farm
https://content.ces.ncsu.edu/growing-raspberries-in-north-carolina
I live in a suburb of Charlotte, NC and see blackberries everywhere, but being from New Orleans originally, I don’t think I’ve ever seen raspberries in the wild in Charlotte and surely not in Louisiana. It may be that I haven’t seen them because my eye isn’t trained, but I’d certainly harvest them on the hillsides if I found them! Like you say, a LOT less work! 
Extremely helpful and thanks for the link to the NCSU pub, thanks! I didn’t realize there was an evaluation site in Salisbury. I will need to learn more about that and try to visit.