Fruit Bud Damage from Cold Temperatures

Fruit growers in central Kansas often wonder at what temperature fruit buds are killed. The following will give you some guidelines but remember that the actual damage is going to be influenced by the weather before the temperature drops. An extended warm spell before the cold snap may result in more damage due to a loss in cold hardiness.

Apple10% kill (°F)90% kill (°F)
Silver tip152
Green tip1810
Half-inch green2315
Tight cluster2721
Petal fall2825
Fruit set2825
Pear10% kill (°F)90% kill (°F)
Swollen bud151
Bud burst 207
Green cluster2615
White bud2622
Petal fall2824
Fruit set2824
Peach10% kill (°F)90% kill (°F)
Swollen bud182
Half-inch green235
Petal fall2825
Fruit set2825
Tart Cherry10% kill (°F)90% kill (°F)
Bud burst175
Green tip2514
Tight cluster 2617
Swollen bud 2724
Bloom 2825
Petal fall 2825
Fruit set 2825
Plum and Prune10% kill (°F)90% kill (°F)
Swollen bud141
Bud burst183
Green cluster2616
White bud 2621
Petal fall 2823
Fruit set 2825
Apricot10% kill (°F)90% kill (°F)
First white2414
First bloom2519
Full bloom2722
In the shuck2724
Green fruit2825

To determine whether a fruit bud is alive or dead, use a sharp knife or a single edge razor blade and cut buds in half.  Remove buds from the tree and make the cut starting at the base and cutting upward.

If the fruit pistil (see image) in the center is greenish white to cream color, no damage has been done. However, if the fruit pistil is dark brown or black, it has been killed. Cut a number of buds to find a percentage killed.      Some loss of buds is actually beneficial for peaches and apples. These trees often produce far too much fruit and require thinning for top quality. As a rule, we want an apple or peach an average of every six to eight inches on a branch. We can often achieve this with only 10% of the original buds developing fruit.  

It is possible to give some protection to fruit blossoms from freezing by covering the tree with a bed spread, blanket or similar fabric. Old-fashioned Christmas lights distributed around the tree will help to give additional protection. The newer, smaller Christmas lights do not give off enough heat and are not recommended. Of course the practicality of this method of protection depends upon the size and number of trees.