Camellia Dieback please help
I have just under 200 camellias in my north Florida yard. Shi Shi gashira, chansonette, Nuccio's gem, nuccio's pearl, high fragrance, Ted Knudsen, Nuccio's Bella Rossa, Glen 40, Magnoliaflora, Apple Blossom, Mine no yuki, Debutant, Omega, any many many more unnamed varieties that were here when we moved in.
This year, my sasanquas and even several japonicas developed die back. It's ravaging some of them. I had been spraying them preventatively with liquid copper fungicide. I fertilized and also used all season horticultural oil as a disease preventative. My job had me out of town for 6 weeks. I paid a service to spray the yard and shrubs while I was gone. I came back to find tons of tip die back on the sasanquas and even a few of the japonicas- including some of the 60 year old ones!!!
I have tried spraying with thiophanate-methyl. Waiting a week and then pruning away the diseased branches, dipping the pruners in a dilute bleach solution between each and every cut (I also had some fungicide in the solution, too). Then after pruning I sprayed the plants down in fungicide (application #2). One week later the die back is progressing and developing on new branches. So, I applied a granular azoxystrobin and watered it in. I cannot find any liquid forms of azoxystrobin.
Three days later I sprayed with liquid copper.
Still finding newly affected branches.
What in the world can I do to halt this progression? I am in immediate danger of losing just under 50 plants. That's no small investment.