2025 Pennsylvania Tree Fruit Maturity Report - July 29

Introduction

Welcome to Penn State Extension's weekly apple maturity reports! Maturity metrics for key varieties will be tracked across the state throughout the 2025 season. Informed harvest timing is critical for fruit quality, particularly for apples in mid- to long-term storage. Balancing sugar accumulation, color development, starch clearing, and pressure loss is difficult to manage. These reports serve to provide insight and help inform management decisions.

Conducting Maturity Tests at Home

While this article series will point to trends across the state, it will provide data from only three counties: Adams, Berks, and Centre. Because of this, conducting tests locally can provide specific information to best guide harvest timing. This article on determining fruit maturity and optimal harvest dates has information on the hows and whys behind maturity metrics. Please consider reading the article before interpreting these reports, as it can better explain why each metric is used. It also describes the tools used, some of which are available for modest prices (such as a basic penetrometer), which can support your own maturity testing methods.

Iodine testing and starch index scales are a user-friendly approach to collecting maturity information. The starch iodine index values in these reports are estimated using an excellent new resource from Michigan State University. A PDF version of the booklet is available for free, and printed copies may be available from a local Extension office. Please be aware that the (largely inert) chemicals used in the staining process are no longer available over the counter and require authorization from the federal government to purchase. For information on how to acquire them, contact the authors.

Controlling Harvest Timing

Stop-drop materials are widely used to delay fruit ripening. There are a number of stop-drop products available for use in Pennsylvania. These chemicals, including ReTain®, Harvista™, and NAA products, all interfere with ethylene production in apples. Controlling the harvest window can be beneficial for U-Pick operations by expanding the accessibility of highly desirable varieties into peak fall season. Stop-drops can also be implemented to manage the workflow of orchard crews to ensure that more apples are harvested at peak ripeness. Additionally, delaying harvest can allow for longer exposure to better weather for color development.

Weather and Color Development

Color development is of particular interest this fall as the predicted weather for August in southeast Pennsylvania is quite warm. The predicted highs are currently hovering in the mid-high 80°F, with lows in the mid-high 60°F. The monthly and seasonal temperature outlooks from the National Weather Service predict that Pennsylvania is moving into an above-average temperature period this harvest season. Temperature impacts color development in fruit, though reddening can be encouraged with appropriate management techniques. High temperatures at harvest also affect fruit quality in storage. Consider these handling guidelines from Michigan State University when managing harvest in hot weather.

Adams County

Maturity samples were collected from two orchards in Biglerville; please adjust harvest decisions based on the specific conditions at your site.

As anticipated, Premier Honeycrisp® is moving into the maturity window ahead of standard Honeycrisp. At a starch index of 5.5, it has progressed past the optimal maturity window (3) and is moving towards over maturity (6). Sugar accumulation is good and firmness is close to the recommended firmness for long controlled atmospheric storage (17 lb). Please assess blocks this week to prepare for harvest in the near future. If harvest is delayed to allow additional color development, be aware that fruit left on the tree for more than a week past optimal maturity will not store well. Extended hang time significantly reduces storage life and fruit quality. Consider balancing color goals with storage potential when planning harvest schedules.

Standard Honeycrisp apples in Adams County are still several weeks away from reaching maturity. Current maturity indicators show that the fruit requires additional time to fully develop before harvest. Notably, fruit firmness this year is measuring around 23 lb - lower than the 26 lb recorded at the same time last year, despite last year's harvest occurring approximately two weeks earlier than typical. Research and field observations strongly suggest that extreme heat can reduce fruit firmness, which may negatively impact storage quality. Please take this into consideration when planning harvest timing and storage strategies for Honeycrisp.

For the current season, Honeycrisp is expected to be harvested no later than 1^st September (Dates may vary slightly depending on location.)

Wildfire™ Gala, an early ripening Gala sport, is now mature and moving towards over maturity based on the starch index average (5.4). Color development and sugar accumulation are good at this time. Firmness is still quite high. Please assess Wildfire™ Gala blocks this week to ensure that the starch clearing does not move too quickly before harvest.

Temperatures are expected to exceed 90℉ on Tuesday and Wednesday, so it's critical to move the fruit out of direct sunlight as quickly as possible. The fruit must be cooled promptly to remove field heat. If the fruit is being stored in Controlled Atmosphere (CA) rooms, it is especially important that it first reach a temperature of 40–45℉. Depositing the fruit into CA storage while still warm will lead to increased respiration, and high CO₂ levels can be particularly damaging to some cultivars such as Honeycrisp and Gala.

Figure 1. Top-down view and starch staining of the original strain of Honeycrisp (L) and Premier Honeycrisp® (R). Stained apples are not in the same order as the unstained apples. Photo by Daniel Weber, Penn State Extension.

Berks County

Maturity samples were collected from two orchards in Boyertown; please adjust harvest decisions based on specific local site conditions.

Standard Honeycrisp is still developing in Berks County. The current sugar levels and red coloration will hopefully continue to develop with time.

Differences between the observations in Adams and in Berks counties for Honeycrisp are insignificant with respect to harvest recommendations; Berks growers should review the comments given above, in the section for Adams County.

Centre County

Maturity samples were collected from one orchard in State College; please adjust harvest decisions based on specific local site conditions.

While the firmness in the Centre County Honeycrisp sample was lower than the Berks County sample, Royal Red Honeycrisp® is not as mature. Given the difference in geographic location, this is to be expected.

The other varieties sampled are not sufficiently developed to address at this time.

Reference Data

The data reported above may be compared against the following previously published information. Consulting these tables may be useful when making decisions about optimal storage time based on your storage requirements.

Conclusions

Commercial fruit growers, please note: apple maturity conditions need to be monitored at a local level within one's own orchard. Before chemical products are applied, be sure to comply with current federal, state, and local usage regulations and examine the product label. Product information can be easily obtained online from CDMS.

This series of updates is made possible by a State Horticultural Association of Pennsylvania (SHAP) Extension Grant (Pennsylvania Apple Maturity Program). The authors thank SHAP for the funding and thank the growers participating in these updates and allowing access to their orchards to sample fruit.