I’m in shock, as I didn’t even know she was ill, but I just read this, from Delmar Williams, on a Facebook group:

Her performance of Rite of Spring begins at 1h 9m. She speaks at 21m10s briefly @ 2m HERE.
Julie Giacobassi, English horn San Francisco Symphony from 1981 to 2006 and Honorary Member IDRS, has died after a long illness. Our most sincere condolences to her husband, Zach, relatives including her sister-in-law Beth Giacobassi, bassoon/contrabassoon Milwaukee Symphony and members of the San Francisco Symphony. I’ll you know if I see an obituary.

Update: I have since read that she suffered from ALS.