Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Losses in tree fruits due to the late March freeze are now more obvious. However, damage will not be fully known for several more weeks. Fruits that seemed to be set often do not develop because the embryos have been damaged.
Plum, pluot, plumcot, and apricots have 80-100% losses. Peaches and nectarines are more variable depending on location and variety. Some varieties are carrying only a 10-20% (or less) crop, others are in the 40-60% crop range. However, certain later flowering varieties are carrying a heavier (near full) crop. What remains to be seen is if there is hidden freeze damage to existing fruit leading to continued drop.
Fruit drop is a result of unfertilized or poorly fertilized seeds, freeze damage to buds and flowers (as in this year 2022), competition between fruits, or shading. In other years, fruit drop may be due to poor pollination as a result of cold, rainy weather during bloom in self-fertile fruits such as peaches, or poor insect pollinator activity during flowering in insect pollinated fruits such as apples. In stone fruit, some fruit that is not fertilized will remain on the plant for 25-50 days after bloom and then will drop before pit hardening starts. This is what we will see in cold damaged peaches and nectarines over the next few weeks.
Cold damaged peaches
You can’t always tell from outward appearances if fruit was damaged by freeze. The best way to tell is to cut the fruit in half. The center of the developing fruit should be green, not brown like these peaches. A brown peach is a dead peach, and these will eventually fall off the tree before maturing. Read more at: https://growingsmallfarms.ces.ncsu.edu/2016/04/freeze-damage-to-local-fruit-crops/