Hi C24,
I have just a few observations about your freeze protection set up . . .
1] amount of water? - That is indeed a lot of water to dump on that tree. Possibly one of those brass Dramm Fogg-It Nozzles* could put enough moisture into the air to buffer the cold, but with a much lesser output of water, plus it's at the mercy of the wind that night (see #2 below)
2] wind direction - Might blow the water aside leaving part(s) of the tree unprotected. Some provision should be made so that the position of the water (or mist) source could be quickly accommodated to altered wind direction, critically important in case the wind happens to shift direction at some point during the night!
3] Water in hose and PVC could freeze - Ufff! You don't want that, so it might be practical to wrap the hose and PVC upright, etc., to insulate them.
* Just FWIW . . . I've used Fogg-It Nozzles (fine or superfine) mounted on top of an eight-foot metal conduit shoved into the ground on a number of occasions to protect my orchids and other tropical plants on a few really cold nights. Some of the orchids wound up with icicles hanging from them but the water kept the plants above freezing and saved them. I left the mist running the next morning just until the icicles had melted/dissolved away. These nozzles are easy to use since they have standard female threads so they screw right onto a regular garden hose.
The Dramm FoggiIt Nozzles are available on Amazon if you are interested:
https://www.amazon.com/Fogg-Watering-Nozzle-Pack-gpm/dp/B00W9X0HDQ/ref=sr_1_2?dchild=1&keywords=Dramm+Fog-It+Nozzle+GPM+Brass&qid=1606372534&s=lawn-garden&sr=1-2 OK — Just a few comments on how I handled a similar situation with my tender plants.
Fruit-aholic, save that tree!!
Paul M.
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