Wind… if the direction is right can also cause problems… frost type conditions when it is 35F on my back porch.
I am on a ridge top with deep hollows near by… from my orchard on ridge top… you can walk a quarter mile south west and drop 250 ft in elevation.
I have seen the wind blowing up out of that hollow and across the ridge where my orchard is and off the other side. Often with a cold fog (more moisture) traveling across the orchard ridge and off in the deep hollow on the other side.
Having deep hollows near by for the cold air to sink into… is good… until the wind decides to blow that cold air up out of the hollow and thru your orchard.
Mulberry leaves and fruit must just be more cold sensitive than most… pears, apples, plums, che, goumi and most persimmons had no damage at all.
And Lawson Dawson mulberry sure seems to be more cold hardy than the others I have… it suffered very little leaf tip damage… and retained its fruit. The 4 others got toasted pretty bad losing all leaves and fruit.
TNHunter