In the eastern half of the United States the plum curculio.

Sep 21, Post bloom and after pollination and fertilization, the petals of the peach blossoms drop or fall off of the tree. This stage is also called “shucks on” or “in the shuck.” Shuck Split.

Gardening Question: I have a peach tree in Irvine. The tree is a couple years old, last year giving a nice yield of delicious peaches. This year, the tree had lots of blooms that appeared to be turning to peaches.

Recently I've noticed several of these little peaches are falling off the tre, Southern California Gardening, Organic Gardener, Organic Vegetable Gardening, Gardening Organic.

Oct 28, Apply this mixture to the tree when the buds turn pink, when they bloom, when the petals fall from the blooms, when the shucks on the pollinated flowers split, when the shucks fall off. Sep 15, Flowers in full bloom and newly set fruit freeze when the temperature reaches 28 or 29 degrees Fahrenheit. The fruit's embryo turns black and falls off instead of developing into a peach. Applying insecticides such as spinosad (Table 2) at petal fall and again at shuck-split can help control peach twig borer.

Spinosad or permethrin mixed with a dormant oil applied during the winter can also be effective for peach twig borer and scales.