2025 Pennsylvania Tree Fruit Maturity Report- September 16
Crimson Crisp coloring beautifully in Centre County. Photo: Copyright © 2025 Marley Ewick and Penn State.
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
The weather so far this harvest season has been excellent for apple color development – and this week is no exception, with high temperatures in the low 80°F and low temperatures in the 50°F. Several small rain events are anticipated throughout this week. The rain predicted on Wednesday, 9/17, could contribute to cracking in over mature fruit still on the tree.
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 (Adams County). Please adjust harvest decisions based on the specific conditions at your site.
| Date | Mass (g) |
Diameter (in) |
Red Color (%) |
Background (1-5) |
Firmness Average (lb) |
Starch Index (1-8) |
Soluble Solids (°Bx) |
|---|---|---|---|---|---|---|---|
| Crown™ Empire | |||||||
| 9/15 | 170 | 2.9 | 88.0 | 3.0 | 20.6 | 4.7 | 12.5 |
| 9/8 | 158 | 2.9 | 92.5 | 1.7 | 20.5 | 4.3 | 12.2 |
| Golden Delicious | |||||||
| 9/15 | 270 | 3.5 | 0.9 | 1.7 | 17.5 | 5.6 | 13.0 |
| 9/8 | 267 | 3.3 | 0.8 | 1.5 | 18.4 | 4.1 | 13.2 |
| 9/2 | 197 | 3.0 | 72.6 | 1.4 | 21.7 | 4.6 | 11.8 |
| 8/25 | 274 | 3.4 | 0.0 | 2.3 | 18.5 | 2.9 | 11.1 |
| Ludacrisp® | |||||||
| 9/15 | 260 | 3.3 | 28.0 | 1.4 | 18.0 | 6.4 | 14.0 |
| 9/8 | 242 | 3.2 | 8.0 | 1.5 | 19.0 | 4.9 | 13.0 |
| Nittany | |||||||
| 9/15 | 262 | 3.4 | 25.0 | 1.7 | 20.0 | 2.4 | 11.1 |
| Red Delicious (Super Chief® / Sandidge cv.) | |||||||
| 9/15 | 256 | 3.3 | 98.3 | 1.0 | 17.4 | 4.1 | 11.1 |
| 9/8 | 264 | 3.3 | 95.1 | 1.1 | 19.2 | 3.4 | 11.7 |
| 9/2 | 206 | 3.1 | 91.3 | 1.3 | 19.3 | 3.1 | 11.2 |
| 8/25 | 190 | 3.0 | 83.0 | 1.8 | 19.6 | 2.6 | 9.0 |
Empire (Crown™)
Crown™ Empire is moving into its maturity window. The fruit firmness is still high at 20.6 lb, but the starch clearing (4.7) is moving along. The sizing, color, and sugar content are strong currently. This variety should be monitored closely this week and harvested shortly.
Golden Delicious
Golden Delicious is now towards the end of its harvest window in Adams County. While fruit firmness is still decent at 17.5 lb, the starch index values have progressed to 5.6. Fruit harvested this week should be directed towards short-term storage or fresh market sales.
Ludacrisp®
Ludacrisp® is currently mature and should be harvested shortly. While this variety is typically harvested at the higher starch index value, the current 6.4 value indicates that this variety will soon be moving towards overmaturity. The sugar content (14 °Bx) is excellent, and the fruit firmness (18.0 lb) maintains integrity, but continuing to hold this fruit on the tree to increase the red coloration (28%) could reduce this fruit’s storability.
Nittany
Between the lower starch index value at 2.4 and the higher fruit firmness at 20.0 lb this week, Nittany is not currently ready for harvest. However, it should be watched in the next two weeks. This will give the currently moderate 11.1 °Bx sugar content time to further advance.
Red Delicious (Super Chief® / Sandidge cv.)
Red Delicious is mature in Adams County. The fruit firmness and starch index values are progressing substantially for the first time in three weeks. The red coloration is excellent. While the sugar accumulation is not ideal at 11.1 °Bx, holding this fruit on the trees can reduce the storability of these apples.
Berks County
Maturity samples were collected from two orchards in Boyertown; please adjust harvest decisions based on specific local site conditions.
| Date | Mass (g) |
Diameter (in) |
Red Color (%) |
Background (1-5) |
Firmness Average (lb) |
Starch Index (1-8) |
Soluble Solids (°Bx) |
|---|---|---|---|---|---|---|---|
| Golden Delicious | |||||||
| 9/15 | 151 | 2.4 | 7.3 | 2.5 | 15.4 | 3.9 | 12.0 |
| 9/8 | 171 | 2.4 | 20.0 | 2.3 | 15.9 | 3.6 | 12.3 |
| 9/2 | 161 | 2.3 | 17.0 | 3.0 | 17.3 | 2.7 | 11.8 |
| Red Delicious | |||||||
| 9/15 | 159 | 2.4 | 96.0 | 1.0 | 17.3 | 5.1 | 11.4 |
| 9/8 | 174 | 2.3 | 97.5 | 1.0 | 18.6 | 2.9 | 11.4 |
| 9/2 | 153 | 2.3 | 90.0 | 1.0 | 18.8 | 2.8 | 10.3 |
The fruit tested in Berks County has not reached the same size as those in Adams County, most likely due to a heavy crop and the lack of rain during the past month.
Golden Delicious
Golden Delicious is moving into full maturity in Berks County. The firmness is continuing to decline (15.4 lb), and the starch index value is rising (3.9). The sugar accumulation did not increase this week, but keeping this fruit on the tree will reduce its storage potential. Any remaining Golden Delicious should be harvested this week.
Red Delicious
Red Delicious is entering the maturity window in Berks County. While the starch index value increased to 5.1 this week, the sugar content remained exactly the same at 11.4 °Bx. Given that the starch index value is moving towards overmaturity and the fruit firmness is now dropping, consider harvesting fruit intended for long term storage shortly. Fruit with a shorter storage window can be monitored on the tree to attempt to increase the sugar accumulation in the fruit.
Centre County
Maturity samples were collected from one orchard in Centre County; please adjust harvest decisions based on specific local site conditions.
| Date | Mass (g) |
Diameter (in) |
Red Color (%) |
Background (1-5) |
Firmness Average (lb) |
Starch Index (1-8) |
Soluble Solids (°Bx) |
|---|---|---|---|---|---|---|---|
| Ambrosia | |||||||
| 9/15 | 171 | 2.8 | 65.0 | 1.9 | 21.5 | 2.1 | 13.2 |
| 9/8 | 181 | 2.9 | 50.0 | 1.8 | 20.6 | 1.2 | 11.9 |
| Crimson Crisp® | |||||||
| 9/15 | 163 | 2.8 | 94.0 | 1.3 | 22.2 | 4.7 | 14.1 |
| Fuji (Aztec®) | |||||||
| 9/15 | 166 | 2.8 | 57.5 | 3.3 | 21.4 | 1.8 | 12.6 |
| 9/8 | 171 | 2.8 | 40.5 | 2.9 | 20.7 | 1.9 | 11.8 |
Ambrosia (DT2 cv.)
Ambrosia is underripe in Centre County this week. The starch index value (2.1) progressed from last week (1.2). However, the pressure remains high (21.6 lb) which will give the red coloration and the already excellent 13.2 °Bx sugar content time to further develop. Once the starch clears further, this will be a great crop.
CrimsonCrisp®
CrimsonCrisp® has excellent color and sugar accumulation. Despite the advanced starch index value (4.7), this variety still needs to develop flavor on the tree. The high pressure (22.2 lb) will allow these apples time to fully mature on the tree. Keep a close eye on CrimsonCrisp® to balance flavor development with high starch index levels this week. Consider that this variety may not store long term optimally with overmature starch levels.
Fuji (Aztec®)
Aztec Fuji® is not mature yet in Centre County. While the sugar content (12.6 °Bx) and color progressed in the last week, the starch index value (1.9) and pressure (21.4 lb) are holding steady. This will allow the crop to continue maturing the positive characteristics prior to harvest. We will continue to monitor Aztec Fuji® in the next few weeks.
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.
| Mass (g) | The mass (commonly "weight") of the fruit in grams. Despite measurements being taken using SI units (metric), most are converted to the units common in the US. This is the one exception. To convert to ounces, divide grams by 28.3 (or round up to 30 g/oz for a close estimate.) |
| Diameter (in) | The maximum width of the apple as measured across the cavity. |
| Color (%) | The visual percentage of red color from 0 to 100%, indicating the surface area covered in red coloration and the intensity of red coloration. |
| Background Color | 5 = green, 1 = yellow. Background color evaluated against the standard found in Simons, L.R. (1948) Ground Color for McIntosh Apples, Cornell Extension Bulletin, Number 750, last accessed July 29, 2024. |
| Firmness (lb) | Pounds of pressure was measured using a handheld FT 325 Penetrometer (Berks, Centre) or a Güss Fruit Texture Analyzer (Adams). |
| Starch Index | 1 = 100% starch, 8 = 0% starch. Starch indices evaluated against standards found in Beaudry, R. et al. (2023) Starch Index Scale, Michigan State Extension, last accessed July 29, 2024. |
| Brix (°Bx) | Degrees Brix, a measure of soluble solid content ("sugar") in apple juice equivalent to 1 g of sucrose dissolved in pure water to form 100 g of solution. Measured with an Atago PAL-1 Pocket Refractometer (Adams, Centre) or a Fisher HDR-P1 handheld digital Brix/RI refractometer (Berks). |
| Variety | Short CA | Mid-CA | Long CA |
|---|---|---|---|
| Early Fuji | 16 | 17 | 18 |
| Empire | 14 | 15 | 16 |
| Fuji | 16 | 17 | 18 |
| Gala | 16 | 17 | 18 |
| Golden Delicious | 15 | 16 | 17 |
| Honeycrisp | 15 | 16 | 17 |
| Idared | 14 | 15 | 16 |
| Jonagold | 15 | 16 | 17 |
| Jonathan | 14 | 15 | 16 |
| McIntosh | 14 | 15 | 16 |
| Red Delicious | 16 | 17 | 18 |
| Rome | 15 | 16 | 18 |
| Variety | Mature | Over-mature |
|---|---|---|
| Early Fuji® | 3 | 7 |
| Empire | 3.5 | 6 |
| Fuji® | 3 | 7 |
| Golden Delicious | 3 | 6.5 |
| Honeycrisp | 3.5 | 6 |
| Idared | 3.5 | 6 |
| Jonagold | 3.5 | 5.5 |
| Jonathan | 3.5 | 5.5 |
| Red Delicious | 2.5 | 6 |
| Rome | 3 | 5.5 |
| Low | Fair | Good | Excellent | |
|---|---|---|---|---|
| All Varieties | < 11 | 11 | 12 | 13 |
| Honeycrisp | < 12 | 12 | 12 | > 14 |
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.
