Freeze Damage in Peaches and Apples and Other Fruit

Introduction

Last Wednesday morning (April 7^th, 2025), temperatures across the region dropped significantly, with observed lows ranging from 15 ℉ to 25 ℉. These temperatures were at least a few degrees lower than what had been forecasted.

At the time of the freeze, peaches were in various stages of bloom, ranging from first bloom to full bloom, depending on the variety and location. As expected, varieties that were in full bloom experienced substantial to severe damage due to the cold. In contrast, varieties that were slightly behind in development, still in early bloom or pre-bloom stages—suffered noticeably less damage.

This report is divided into sections by region, and includes some information on crops other than apples and peaches/nectarines: pear, cherry, and apricot. Tables summarizing observed damage precede discussions of the findings and recommendations for consideration.

Southcentral Region: Adams County

Southern Adams County

Despite this event, most peach varieties are expected to carry a crop, though heavily damaged varieties may see significant losses. Before making thinning decisions or applying chemical thinners like Accede™, it is essential to assess the extent of bud survival. Be sure to evaluate at least 50–100 buds per variety to get a reliable estimate of damage.

Once the level of injury is known, you can tailor your thinning approach accordingly. Accede™ can be a useful tool, but its application rate should be adjusted based on bloom density and freeze damage severity. The labeled rate is 300–600 ppm, equivalent to 10–20 ounces of soluble granule product per 100 gallons of water per acre. A general starting point is 15 oz (450 ppm) per 100 gallons/acre. However, reduce the rate for lightly blooming trees, young trees, sensitive varieties, or those with visible frost damage, to avoid over-thinning.

The percentage bud damage indicate that no thinning may be necessary.  Local assessments of pear blocks should be conducted to determine if thinning is warranted, and that with care.

In southern Adams County, some cultivars were at the very early pink to late tight cluster stage during the freeze, and several blocks experienced extensive damage. In one Gala block, we observed approximately 60–70% bud damage, indicating that very little to no thinning will be necessary. In fact, blossom thinning is not recommended for this block. Depending on the final fruit set, a light fruitlet thinning spray may be sufficient later in the season. Buds/flowers evaluated from three different branch heights—high (H), medium (M), and low (L) within the canopy

Central Adams County

For Honeycrisp and other apple cultivars such as Gala and Fuji in central Adams County, any buds that had begun to show pink—particularly king blooms and some terminal laterals—exhibited damage following the freeze event.

Damage to the reproductive organs is obvious when the bud is bisected with a sharp knife.  The following are Honeycrisp apple buds exhibiting dead pistils.  The collection of five buds on the right shows damage to the king blossom but no apparent damage to the laterals.

Southeastern Region: Delaware County

At this particular site, frost protection measures such as orchard heating (burning fires) were implemented during the recent freeze event, and these efforts appear to have been largely successful in preventing severe damage, especially in peaches, nectarines, and apples. Most of the stone fruit varieties—including peaches, plums, and some pears—were in full bloom at the time of the freeze, a stage particularly vulnerable to low temperatures. Despite this, the survival data indicates that the heating strategy helped mitigate the cold’s impact across much of the orchard.

For example, Redgold nectarines in a low-lying section still had an impressive 80% flower survival, and apples such as Red Delicious and Pink Lady™ in the late pink stage maintained 82% and 100% survival, respectively. Pears and peaches also performed well, with the Crispie™ pear and Avalon™ peach showing 92% survival each. Galaxy peach and plums had moderate levels of damage, with 60% and 68% survival, respectively. The only variety that exhibited significant injury was apricot, which was in full bloom and showed just 8% survival, highlighting its sensitivity to freeze conditions.

Central Region: Bedford County

Table 6 below summarizes freeze damage assessments conducted across several peach and apple varieties, with buds evaluated from three different branch heights—high (H), medium (M), and low (L) within the canopy.

The Bedford site utilized wind machines and a Frost Dragon for many of its stone fruit acreage as part of its frost protection strategy. The results show clear variation in bud mortality depending on both variety and bud position in the tree.

In the V-Block Peaches, overall bud mortality was relatively low at 10%, though the lower canopy showed higher damage (29%), suggesting that buds closer to the ground were more exposed to colder air during the freeze. Glenglo™ exhibited moderate overall damage at 13.4%, with the greatest loss (40%) again observed in the low canopy. Glohaven and Early Redhaven showed strong bud survival, with minimal overall damage (both at 5.3%), indicating good freeze tolerance or protection across canopy levels.

In contrast, cherries were highly susceptible at the time of the freeze. Cherries which were in the first white stage had significant losses ranging from 50-100% depending on the variety and location.

Royal Red Honeycrisp®, located at a known frost-prone site, suffered significant losses with an overall mortality of 52%; the mid-canopy buds were most affected, with 72% mortality. Ultima Gala®, on an elevated site, had better outcomes with only 16% overall bud loss, and notably low damage (4%) in the lower canopy, possibly due to better air drainage or temperature moderation at that location. These findings underscore how cold air settling during freeze events can disproportionately affect buds in the lower and mid-canopy and highlight the need for canopy-level observations when assessing freeze damage and planning subsequent thinning or crop load management strategies.

Central Region: Centre County

At Rock Springs, temperatures dropped to 19 ℉ for several hours, followed by a more severe dip to 17 ℉ for approximately one hour. This prolonged exposure to sub-freezing conditions resulted in notable freeze damage across several apple varieties, particularly in low-lying, cold-prone areas of the orchard. While some blocks showed relatively high bud survival, others experienced significant losses, highlighting the microclimatic variability within the site.

Table 7 below summarizes bud survival percentages for key varieties across different blocks. In Block C, a known cold pocket, survival rates were dramatically lower. Fuji dropped to 12%, Pink Lady™ to 38%, and Honeycrisp to 63%, indicating severe freeze injury in this part of the orchard.