Mild frost may produce a corky ring around the surface of the young fruit, usually near the calyx end.
Frost occurring from petal fall to when fruit are about 0.33 inch in diameter may cause internal freezing
of the fruit. Externally there may be no symptoms, but as the fruit matures it becomes flattened or distorted
by development of internal pockets of dead tissue. On occasion, internally damaged fruit drop from trees
a week or two after injury.
To reduce the likelihood of frost injury, conserve heat
by keeping the vegetation under trees mowed short, so that
the soil surface is firm and moistened. If overhead sprinklers
are available, use them on apples and pears to prevent frost
injury when low temperatures occur during bloom. Trees can
be protected from frost injury by covering them with floating
row cover or using protective shelters if freezing conditions
occur during bloom or early fruit growth. These covers should be prevented from touching the tree.
Internal pockets of dead tissue