Tree Fruit Maturity Report — September 26, 2025
Maturity Report
Apples
McIntosh apples at Highmoor Farm are dropping off the tree in all blocks indicating that the window has passed for harvesting storage apples. Our blocks were not treated with ReTain. Starch index and Delta Absorbance (DA) numbers have not changed from last week, but I measured the fruit still on the tree which are behind in ripening compared to the fruit that have dropped. Limb shaking causes fruit to drop which means excessive fruit drop is likely to occur in the next week.
Honeycrisp blocks have been spot picked once. Fruit remaining on the tree are at a stage of ripening that is still ok for storage, but are very susceptible to chilling injury. Continue to condition apples first for 5 to 7 days. Temperatures in cold storage should remain above 36 ºF for protection against chilling injury. If Honeycrisp apples have lost all green peel color and have turned yellow, they have passed the stage where they will remain in good condition in storage. Honeycrisp apples will develop a greasy peel and will lose flavor in storage if harvested too ripe.
Cortland apples have reached a stage of ripening where they are suitable for storing.
Macoun has reached a stage where it is suitable for storage. This variety is known for not holding up well in long-term storage and will develop internal browning if stored past mid November. 1-MCP can extend the storage duration by preventing this senescence.
Golden Delicious and Empire showed some ripening in the last week and are ready to harvest for long-term storage.
Fuji and Evercrisp changed very little in the last week, and not yet ready to harvest for storage.
| Variety | Starch Index 9/12/25 | DA 9/12/25 | Starch Index 9/16/25 | DA 9/16/25 | Starch Index 9/19/25 | DA 9/19/25 | Starch Index 9/26/25 | DA 9/26/25 |
|---|---|---|---|---|---|---|---|---|
| Honeycrisp | 5.6 | 0.77 | 6.1 | 0.75 | 6.4 | 0.58 | 7.6 | 0.55 |
| McIntosh (standard) | 3.7 | 1.72 | 4.7 | 1.86 | 5.4 | 1.78 | 5.6 | 1.90 |
| McIntosh (spur type) | 4.3 | 1.80 | 4.6 | 1.67 | 5.0 | 1.70 | fruit are dropping fast | – |
| Cortland | 1.4 | 1.69 | 1.3 | 1.69 | 1.7 | 1.53 | 2.2 | 1.35 |
| Macoun | 2.4 | 1.93 | 2.7 | 1.85 | 2.3 | 1.88 | 3.3 | 1.76 |
| Empire | – | – | 2.2 | 1.71 | 2.1 | 1.67 | – | – |
| Fuji | – | – | 1.6 | 1.92 | 2.3 | 1.79 | – | – |
| Golden Delicious | – | – | 1.4 | 1.52 | 1.5 | 1.65 | – | – |
| Evercrisp | – | – | 1.0 | 1.42 | 1.2 | 1.36 | – | – |
| Sweet 16 | 2.4 | 1.69 | 2.7 | 1.66 | 3.2 | 1.46 | – | – |
* DA is a measure of chlorophyll breakdown in the peel which parallels ripening. Numbers decrease as fruits ripen. Gala and Honeycrisp readings between 0.8 and 0.3 indicate sufficient maturity for storage. McIntosh DA has not closely followed harvest maturity in years past and remains much higher than in other varieties. Cortland and Macoun DA, in the past, has decreased below 1.5 during the harvest window.
The following is a rough guide to what the starch index numbers mean for apple ripening:
1 – 2: indicates lack of starch breakdown and generally unripe.
3: partially ripe, but prone to disorders in long-term storage.
4: typically ready to pick for long-term storage.
5 – 6: indicates good flavor and ready for general harvest or harvest for short-term storage.
7 – 8: indicates fully ripe, too ripe for long-term storage.
Starch Index Scale
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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