Tree Fruit Maturity Report — October 9, 2025
Maturity Report
Many of us now grow varieties that ripen very late but are vulnerable to the first freeze in fall. A freeze is expected tomorrow morning in some locations. Predicted low temperatures for the Monmouth area are expected to be around 30 ºF, but it could get colder in low-lying areas. The temperature may not be cold enough to freeze apples if it remains above 29 ºF since the sugars can lower the freezing point within the fruit. If apples freeze, it’s best to let them thaw first before harvesting them. They will have a short storage life and will lose some firmness.
Apples
Golden Delicious apples have changed from green to yellow in most fruits indicating that they will soon no longer be appropriate for long-term storage. A few fruits remain green, and these should be ok in long-term storage. They become over-mature for storage when starch index is past 6.0.
Fuji starch index and DA changed very little in the last week, but this variety has developed enough flavor and can be picked for long-term storage. The flesh has remained very dense which could be a problem in CA storage with its low oxygen. They become over-mature for storage when starch index is past 6.5.
Evercrisp starch index has not changed since last week, but good flavor has developed. They should be ok for storage, but all my apples have a mild case of watercore. This means they are at risk of developing internal browning in long-term storage but should be ok for a short storage period of one month.
| Variety | Starch Index 9/19/25 | DA 9/19/25 | Starch Index 9/26/25 | DA 9/26/25 | Starch Index 10/2/25 | DA 10/2/25 | Starch Index 10/9/25 | DA 10/9/25 |
|---|---|---|---|---|---|---|---|---|
| Fuji | 2.3 | 1.79 | 2.2 | 1.75 | 2.5 | 1.57 | 2.4 | 1.55 |
| Golden Delicious | 1.5 | 1.65 | 3.5 | 1.57 | 4.5 | 1.18 | 5.6 | 1.04 |
| Evercrisp | 1.2 | 1.36 | 1.4 | 1.23 | 1.9 | 1.10 | 2.0 | 0.98 |
* DA stands for Delta Absorbance and is a measure of chlorophyll breakdown in the peel which parallels ripening. Numbers decrease as fruits ripen.
Additional Resource
Variety-specific starch indices for determining when to harvest can be found at this Michigan State Univ. Extension website: MSU Starch Scale – Booklet rev 02A
Renae Moran
University of Maine Cooperative Extension: Tree Fruits
PO Box 179
Monmouth, ME 04259
(207) 933-2100
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