Critical Temperatures for Frost Damage USU

One should note the two documents below may use different terms for each development stage. Awareness of regional difference in nomenclature might settle arguments and reduce confusion.

CriticalTemperaturesFruitTrees.pdf (2.4 MB)


FROST on BUDS PictureTableofFruitFreezeDamageThresholds.pdf (721.8 KB)


Great reference. I’ve learned that most fruit trees have a little more bud hardiness than you probably initially think, not that we don’t still have issues!

Ernie’s Choice peach.

Tomcot Apricot

Both look like first swell to me so far.

Apples aren’t doing a damn thing yet.

I added a second document to the first post. The second extension service uses different terms for each stage. Just wanted to highlight this since many an argument and confusion arises from the different use of terms that may just be regional preferences.

I was trying to determine when to spray Indar and the product literature said to do it at the red bud stage. Plums of course do not typically have a red phase and the Critical Temps doc doesn’t mention Red bud. Red Calyx is likely the same but for other fruit like the pears several descriptions are different.

Glenglo peach today.