Figure 1.) Cold damage on apples (left) and peach (right). Photos by C. Walsh.
Cold Damage on Early Blooming Apples and Peaches
Due to last week's cold nights, cold and frost damage has been reported on early blooming peach and apple trees. Freeze can damage flowers, fruit buds, and young fruit. Injury to the flower pistils reduces and prevents pollination, while injury to the ovaries kills flowers. Damaged flowers will turn brown, wilt, become mushy, and often drop from the tree (Figure 1). Late-season freezing temperatures may also cause cracking and splitting of fruit skin. The level of freeze damage is directly related to cold intensity and duration, variety and cultivar of the fruit tree, and bud developmental stage.
Often, freezes will only damage some of the flowers, such as the most developed ones or flowers at the bottom of the tree. With large-fruited fruits such as apples, peaches, and pears, losing ~50 percent of the flowers is often not devastating to yields since growers may only want a small percentage of the flowers to become fruit. For small-fruited fruits such as blueberries and grapes, many small fruits are needed for a full crop and a good yield. Crop losses due to freezing temperatures are almost always significant in cherries.
To determine the percentage of damage following a freeze, growers can gather, cut open, and examine ~100 flowers and buds for brown to black discoloration of the fruit pistil. Flowers and buds should be collected from differing heights within the tree and locations within an orchard or orchard block. Colorado State University Extension has a nice resource entitled Evaluating Tree Fruit Bud & Fruit Damage from Cold, which provides more information on evaluating different fruit tree crops for cold damage.
This article is featured in the Vegetable and Fruit News, Vol. 16, Issue 1.
Vegetable and Fruit News is a statewide publication for the commercial vegetable and fruit industries and is published monthly during the growing season (April through October). Subscribers will receive an email with the latest edition.
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