My neighbor has some wild plums and peach trees that are blooming like crazy but 23f is coming. What should he do to help them?
Get up before daylight and spray them with water ! Water is supposed to get any frost off the blossoms ! Frost is what hurts them they say ! Frost has never hurt my fall pears though,, peaches plums ect may be different ! This is what old timers say to do ! Not sure it works !
As Mart said, giving the buds a coating of water will allow the buds to be safe under a thin coat of ice. In Florida, the citrus farmers, when faced with a freeze, light "smudge pots" and the smoke keeps the air temperatures above freezing. I don't recommend smudge pots.
When this happens here, I pack my buds in with fleece. I know the ice coating is something that would work if one could do it properly, but I find the fleece thing works well for me.
Here's a chart to stew over. Maybe the damage won't be too bad? Fruit bud freeze damage. Your neighbor might lose a lot of flowers this time. If it's only, say, 50% kill, it might just mean fewer but larger fruit. I thin mine manually by about 75% - 90% each year to get better fruit. This site says you can lose up to 90% of flower buds to frost without a reduction of harvest. I can't grow apricots because the trees come out of dormancy too soon and are killed by late freezes here. Peaches and plums usually do OK for me. For the home orchardist, Full size trees, I don't know if there's lot to be done. Misting and smudge pots help for big time orchards. I hope your friend's damage is minor.
