Frost damage to almonds

Almonds are susceptible to frost once they begin to flower. As a flower progresses through bloom (i.e. dormant > pink bud > full bloom > petal fall > small fruit), it becomes more susceptible to cold temperatures. Frost killed flowers/small fruits are easy to identify as the color of the tissue changes. Flowers affected by bloom often have wilted petals or blackened pistils. At petal fall and later, the damage often appears as brown or black tissue within the ovary. This can be identified by cutting the flower/nutlet in half.The photo provides a comparison of flowers affected by frost and a healthy flower. Note the darkened, off-color tissue of the three flowers on the right. All of these have been killed by the frost.Flower sensitivity to cold damage has been studies. Additional information on this can be found here.