Protecting apple trees from frost damage
Apple trees, like other plants, can be damaged or killed by freezing temperatures or frost. Ansovino can alert you when forecasted temperatures fall below the critical values at which bud kill occurs.
Image source: Ayudhdhari
The percentage of bud kill which causes crop reduction will vary with each crop. Apples, pears, and peaches may only need 10-15% bud survival.
Approximate critical temperatures for each stage of development at which frost damage starts occurring (10% bud kill) after 30 minutes exposure are:
-9 °C (bud stage: silver tip and green tip)
-5 °C (bud stage: half-inch green)
-2 °C (bud stage: from first pink to full bloom)