2026 Pennsylvania Tree Fruit Maturity Report - August 31

Introduction

Welcome to Penn State Extension's weekly apple maturity reports. Maturity metrics for key varieties will be tracked across the state throughout the 2026 season.

In this stressful year, with crops decimated by multiple springtime freeze events and hot, dry early summer weather, informed harvest timing recommendations are critical for fruit quality, particularly for apples in mid- to long-term storage. Balancing harvest decisions against sugar accumulation, color development, starch clearing, and firmness drop is difficult to perform in a normal year. These reports serve to provide insight and help inform management decisions.

Out of respect for our collaborators' need to squeeze out as much profit as possible from their available fruit, sampling of varieties may occur a week or more later than in previous years in order to reduce Penn State Extension's impact on their harvest. Please bear this in mind as recommendations this year may require quick action.

A Chance Observation

This week’s report includes an apple variety that is probably unfamiliar to most readers: FyreFly®. A Golden Delicious × Cox’s Orange Pippin cross, this apple is (at this time) unique to our collaborators at Hollabaugh Bros., Inc. It is included here because testing was requested by Hector Mateos, and the authors figured it would be an opportunity to introduce this new Pennsylvania-bred variety to the audience.

A chance observation made when collecting fruit in the FyreFly® block this week provided an opportunity to illustrate a couple of basic production concepts worth mentioning to newer growers (Figure 1). If the reader understands the concepts of self-incompatibility in apples and overlapping bloom times, and how to deal with them effectively in a production environment, nothing will be lost by skipping right to the data analysis for the week.

Unlike peaches, most apple trees require a different variety nearby to produce pollen capable of fertilizing the egg (technically ovule) and polar nuclei in the ovary. Self-incompatible plants carry unique combinations of specific mutations of a gene or genes that intentionally prevent the plant from pollinizing itself. There are a variety of evolutionary reasons why this system exists in plants that, for the apple grower, are largely immaterial. What is important: no compatible pollen, no fruit.

If an apple block appears to be unproductive and all other cultural practices applied ought to result in an abundant crop, it may be due to an insufficient amount of compatible pollen. There are other factors in play, too, such as the timing of when viable and compatible pollen is available, especially if the block is surrounded by trees with non-overlapping bloom periods.

A way to get around these problems is to intersperse among the desirable variety (e.g. FyreFly®) an apple or crabapple variety that produces pollen that is not only available when the flowers are receptive to pollination but is also genetically compatible. Only a handful of trees per acre are needed to have an effect.

In Figure 1, a tree that is obviously of a different variety was observed within the block. This illustrates the second point of this discussion: the size, shape, and most obviously, color, of the fruit distinguishes it from FyreFly®. When interplanting pollinizers, it is wise to select one that produces fruit that is trivially distinguishable to even untrained crews conducting the harvest, so the fruit of the pollinizer does not contaminate the bin. Crabapples are particularly useful in this regard.

Adams County

Discussion

Last week brought warm, humid conditions to Adams County, with periodic afternoon cloud buildup and scattered thunderstorm chances, typical late-August weather. That instability will continue this week, with a slight chance of showers and thunderstorms each afternoon Tuesday and Wednesday, including the potential for some severe storms. Highs will reach the low 90s Tuesday and again Thursday, with temperatures easing into the upper 80s Wednesday. Conditions become more favorable from Friday onward, with highs dropping into the mid-80s on Friday and the upper 70s to low 80s over the weekend. Sunny and dry conditions are expected into Labor Day. Growers should keep an eye on the midweek storm chances for potential hail and wind, but the second half of the week and holiday weekend look favorable for harvest activities.

Varietal Analysis

FyreFly® (Figure 2) is moving closer to harvest, with fruit averaging 210 g and showing 13.2% red color and a background color index of 1.5. Firmness was 18.2 lb, soluble solids measured 12.5 °Brix, and the starch index has reached 4.4. The combination of increasing starch conversion and slightly declining firmness suggests that this variety is now entering its harvest window. Soluble solids are also at a good level. Fruit intended for storage should be monitored closely, and growers may want to prioritize this variety as harvest progresses.

Jonaprince (Wilton's® Red / Red Jonathan cv.) (Figure 2) continues to show a noticeable difference between external appearance and internal maturity. The fruit averaged 265 g and had an impressive 72.9% red color, with a background color index of 1.4. Despite the strong color, firmness remains relatively high at 18.0 lb, soluble solids are 13.0 °Brix, and the starch index is only 2.9. The color may make the fruit look ready to pick, but the starch data suggest that it can remain on the tree for a little longer. I would continue watching starch development and plan to check the block again soon to prepare for harvesting this variety later next week.

Golden Delicious (Figure 3) fruit averaged 221 g, with a background color index of 1.6, firmness of 18.0 lb, and soluble solids of 11.0 °Brix. The starch index was 2.4, indicating that the fruit still has some time before reaching typical harvest maturity. However, if the fruit is being harvested specifically for processing or medium- to long-term storage, where a starch index around 3 may be appropriate, this block could be approaching the harvest window as early as next week. It would be worth checking the fruit again next week to track starch development and determine whether it has reached the desired maturity and brix level for harvest.

Red Delicious (Figure 3) moved quickly this past week. Mass jumped from 218 g to 284 g and diameter from 3.2" to 3.5", so the fruit sized up substantially. Red color also deepened, from 90.5% to 96.6% coverage, while background color barely shifted. Firmness dropped from 18.9 to 16.3 lbs, soluble solids rose from 9.4 to 10.3 °Bx, and starch index moved from 1.5 to 3.0. There was a decent drop in firmness, and depending on how long the reds are going to be stored, they might be ready for harvest even though the brix could improve a bit.

Berks County

Varietal Analysis

As Berks is finishing up with Gala and Honeycrisp harvests, the Reds are not far behind. Red Delicious was measured for the first time this week at 216 g, with a strong red color already at 75.5% color and a background of 1.2. Firmness came in at 17.7 lb, soluble solids at 10.5 °Bx, and starch at 2.0. They are not ready yet; keep testing them and they might reach into the starch index of 3 next week and be ready for harvest.

Historical Data

The tables below contain the data collected in previous weeks of this year's reporting cycle. It is provided to provide information to growers who may be in regions where these varieties are still developing and to serve as a historical record of the 2026 growing season. Please review the previous weeks' reports for information on harvesting.

Adams County

Berks County

Acknowledgements

Starch index values were determined by referencing the Starch Index Scale published by Dr. Randy Beaudry and the MSU Apple Maturity Program at Michigan State University. The page referenced by the hyperlink provides access to a PDF copy of the document that can be freely downloaded.

Starch indexing for RubyMac® utilized the Cornell scale found in Predicting Harvest Date Windows for Apples by Blanpied and Silsby (1992).

Because of low crop set throughout our usual sampling regions, we are indebted to the following orchards for sacrificing fruit each week to make these reports possible:

• In Adams County, Penn State wishes to thank Hollabaugh Bros., Inc., in Biglerville, and Hector Mateos in particular for his assistance.
• In Berks County, Penn State wishes to thank Keim Orchard and Frecon Farms in Boyertown, and Ben Keim and Steve Frecon especially for their collaboration.

Their kindness and generosity deserves acknowledgement.

Penn State wishes to thank Rice Fruit Company for material support that helps make these reports possible.

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.