2025 Pennsylvania Tree Fruit Maturity Report - September 2

Introduction

Welcome to Pennsylvania State Extension’s weekly tree fruit maturity report! 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.

These reports are collated on a "landing page" (termed a "campaign" by Penn State) that can be bookmarked for future reference. Every report issued will appear on the campaign page, often prior to being sent out via email. Missed a report last week or need to review a recommendation? Reports for the entire season will be collected there for quick access.

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.

Weather and Color Development

Temperatures are rising in Adams County this week, culminating in predicted thunderstorms on Thursday and Saturday. Currently, 0.65 inches of rain is expected. Following this period, the weather is returning to the ideal chilly nights (lows around 50ºF) and warm days (highs in the mid 70ºF). The weather later in the week will help promote reddening. While the rain will be very helpful for sizing up fruits, it can also lead to more cracking in over-mature or light blocks. Overall, this has been a wonderful year for coloring due to the cool weather in the past three weeks, and Pennsylvania Honeycrisp has colored well.

Adams County

Maturity samples were collected from two orchards in Biglerville (Adams County). Please adjust harvest decisions based on the specific conditions at your site.

Golden Delicious

Golden Delicious is currently near the maturity window in Adams County. The pressure is already at 18.5 - 19.0 lb and the starch index values are at 3.1. It has a good size of 3.3 in. The soluble solids are quite high at 13.2 ºBx. The variety is mature for harvest. Depending on harvest purpose and storage needs, this variety should be harvested immediately for long-term controlled atmosphere (CA) storage/processing, whereas it could be harvested in the next week for shorter-term and air storage.

Red Delicious (Super Chief® / Sandidge cv.)

Berks County

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

Gala

Gala apples are progressing into over-maturity with a starch value of 6.4. The pressure has dropped to 16.9 lb. The sugar accumulation is good at 11.2 °Bx. This variety should be harvested as soon as possible. Based on their maturity stage, additional rain might crack the fruit, hence, careful consideration should be given to weather conditions and possibly harvested before a potential rain event.

Golden Delicious

Golden Delicious apples are not quite mature but should be monitored closely in the next week. The sugar accumulation is great at 11.8 °Bx. The starch value is currently averaging 2.7 and the firmness is 17.3 lb. Both values can develop a bit more for optimal maturity, but this variety could easily be mature this week and could be harvested next week.

Red Delicious

Red Delicious apples are moving towards maturity in Berks County. The average starch index value is already at 2.8 and the pressure is at 18.8 lb. The color is currently very well developed and the sugars will have time to improve. While more information in the coming weeks is needed for accurate maturity projections, this variety will become mature in the next few weeks.

Centre County

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

Blondee®

As anticipated, Blondee® is right on track with Gala. The sugar accumulation is excellent, and the starch index progressed to 4.4 this week. This variety should be harvested this week.

Gala (Brookfield®)

Brookfield® Gala has great sugar accumulation in Centre County. The firmness is still high at 19 lb for direct-to-consumer harvests. Gala will become ready for harvest this week in Centre County.

Ginger Gold®

Ginger Gold® is nearing maturity with the starch index value at 3.8 and the firmness dropping to 16.8 lb. Improvements in background color and red blush suggest increasing ripeness. This variety should be harvested this week.

Honeycrisp (Royal Red®)

Royal Red Honeycrisp® fruit size, sugar, and color are continuing to develop, but firmness has dropped to 13 lb, which suggests ongoing softening. The starch index values have developed to 4. Continue monitoring maturity progress closely over the next week.

Conducting Maturity Tests at Home

While this article series points to trends across the state, it provides data from only three counties. 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 Starch Indexing

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.

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.