Fruit Bud Damage from Cold Temperatures

​Fruit growers 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.

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Apple

Stage	10% Kill (°F)	90% Kill (°F)
Silver tip	15	2
Green tip	18	10
Half-inch green	23	15
Tight cluster	27	21
Pink	28	25
Bloom	28	25
Petal fall	28	25
Fruit set	28	25

 

Pear

Stage	10% Kill (°F)	90% Kill (°F)
Swollen bud	15	1
Bud burst	20	7
Green cluster	26	15
White bud	26	22
Bloom	28	23
Petal fall	28	24
Fruit set	28	24

 

Peach

Stage	10% Kill (°F)	90% Kill (°F)
Swollen bud	18	2
Half-inch green	23	5
Pink	25	18
Bloom	27	24
Petal fall	28	25
Fruit set	28	25

 

Tart Cherry

Stage	10% Kill (°F)	90% Kill (°F)
Bud burst	17	5
Green tip	25	14
Tight cluster	26	17
Swollen bud	27	24
Bloom	28	25
Petal fall	28	25
Fruit set	28	25

 

Plum and Prune

Stage	10% Kill (°F)	90% Kill (°F)
Swollen bud	14	1
Bud burst	18	3
Green cluster	26	16
White bud	26	21
Bloom	27	23
Petal fall	28	23
Fruit set	28	25

 

Apricot

Stage	10% Kill (°F)	90% Kill (°F)
First white	24	14
First bloom	25	19
Full bloom	27	22
In the shuck	27	24
Green fruit	28	25

 

​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.   (Ward Upham)