Thanks for contacting Ask An Expert for your plant questions. Your star jasmine appears to be experiencing scorch from this summer’s extreme heat. This pattern is typical of sun scald, rather than disease.

Though fall planting is generally great timing, this past winter was unusually cold. And then the spring was long, wet, and cool. Under these conditions, the roots of new plants may not grow and expand as they would have in less harsh years.

Then, this recent extreme heat wave (as well as the earlier spikes of high temperatures) put a high demand for moisture on the plant. The roots of the jasmine may not have been able to pump enough water to the plant leaves.

Here is a photo of similar injury on rhododendron. 

Keep the plants watered, but not soggy. Using a compost or bark mulch around the base of the plant (two to three inches deep) will help retain moisture and keep the soil cool.  

This year might be a bit of a set-back for the plants, but this is a resilient vine and some TLC can bring them around.

Regards,