Your photos (thank you) seem to confirm your thought that heat is the problem. There is a lot of evidence that says that blueberries are NOT really suitable for growing in the Rogue Valley. There were several "farms" (one on South Stage Rd. and one on Camp Baker Rd. several years ago) that  gave up after fighting the heat. Even overhead shading was not sufficient to protect the plants in the open locations they chose. While heat is the likely culprit, there is also a slight chance the plants suffered from  poor drainage (are you planting on clay soils?) or from not enough acidity in the soil (pH of nearly 5.5 required). Our average pH in the valley, and it does vary slightly from east to west and north to south) is around 6.8 to 7.0 (slightly acid to neutral). I'm sorry you were unsuccessful in your attempt  to grow blueberries. Make a soil test and check the drainage , perhaps install overhead shading before you try again.

You might want to take a branch of the plant to the plant clinic OSu Extension Office at 569 Hanley Rd. Central Point. (on rte. 238) Call them for hours, 776-7371. You can also find information at extension.oregonstate.edu Look under publications: there are several on berries, including two on blueberry culture and varieties:  EC1304 and EC1308. You can read online or download.

As far as I know there is some kind of "clinic" available. the phone number for Josephine County Extension is<personal data hidden>. Their address is 215 Eunguette, which is just before the turnoff for the Fairgrounds. There's a chevron gas station on one corner of Ringuette a

You are more than welcome.