Tree Fruit Newsletter — September 25, 2026
In this newsletter:
- Apple Maturity Report
- Disaster Relief Applications Due November 6
Maturity Report
The storm arriving this weekend is likely to bring enough rain to cause fruit cracking in Honeycrisp and Gala in areas expecting more than an inch of rain. Trees with smaller apples should be less likely to have fruit cracking. Strong winds will likely knock some fruit off trees, particularly McIntosh. In blocks treated with ReTain, it appears to be working so will hopefully ReTain will prevent fruit drop. Good luck to everyone as this storm moves through.
Honeycrisp apples are still ok for long-term storage. Starch breakdown is nearly complete, but peel chlorophyll readings indicate that they are not over-ripe. Based on peel chlorophyll, two ReTain blocks were delayed in ripening compared with two blocks that had no ReTain. The starch index has been unreliable in Honeycrisp this year because of the heavy crop load.
The risk of chilling injury disorders increases with ripening. Continue to condition apples by holding them at warm temperatures for five to seven days prior to placing in cold storage. Temperatures should be in the range of 50 to 80 °F during the conditioning. Honeycrisp storage temperatures should be in the range of 37 to 39 °F to prevent chilling injury. Storage at temperatures below 36 °F can reduce the risk of bitter pit, but a small amount of chilling injury can be expected. Temperatures above 39 °F will increase the risk of bitter pit and loss of quality.
Reminder: Honeycrisp is sensitive to the elevated carbon dioxide that occurs in controlled atmosphere storage. Other varieties are also sensitive when treated with SmartFresh or Hazel. Be sure to include enough hydrated lime in your CA rooms. Diphenylamine (No-Scald) will increase tolerance to carbon dioxide in CA storage, but it’s best to keep carbon dioxide below 1% in the first month of CA storage.
I was not able to measure other varieties this time since I have been busy with my own harvesting for research. However, I did some limb shaking of McIntosh and noticed some fruit drop. This means it is too late to harvest Macs for long-term storage unless they have been treated with ReTain or Harvista. These and other varieties are also sensitive to carbon dioxide buildup in CA rooms and will need hydrated lime or some method of scrubbing CO2.
Reminder: Cortland and McIntosh will develop superficial scald in long-term storage unless treated with diphenylamine. MCP (Hazel or Smartfresh) will prevent it in McIntosh, but not Cortland.
| Variety | Starch Index 9/3/25 | Delta Absorbance* (IAD) 9/3/25 | Starch Index 9/9/25 | Delta Absorbance* (IAD) 9/9/25 | Starch Index 9/14/25 | Delta Absorbance* (IAD) 9/14/25 | Starch Index 9/21/25 | Delta Absorbance* (IAD) 9/21/25 | Starch Index 9/25/25 | Delta Absorbance* (IAD) 9/25/25 |
|---|---|---|---|---|---|---|---|---|---|---|
| Gala | 2.6 | 0.95 | 2.6 | 0.74 | 6.0 | 0.37 | – | – | – | – |
| Honeycrisp | 1.0 | 1.42 | 2.1 | 1.37 | 5.3 | 0.99 | 6.7 | 0.90 | 7.0 | 0.61 |
| Honeycrisp with ReTain | – | – | – | – | – | – | – | – | 7.2 | 0.93 |
| McIntosh, spur-type | 3.0 | 1.95 | 3.7 | 1.89 | 5.0 | 1.88 | 5.6 | 1.67 | – | – |
| McIntosh, (Roger’s) | – | – | 3.9 | 2.04 | 4.5 | 1.99 | 5.6 | 1.69 | – | – |
| Cortland | – | – | – | – | 1.2 | 1.89 | 1.3 | 1.64 | – | – |
| RedCort | – | – | – | – | – | – | 1.3 | 1.47 | – | – |
| Macoun | – | – | – | – | 2.2 | 1.94 | 2.5 | 1.70 | – | – |
* IAD 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 0.4 indicate sufficient maturity for storage. McIntosh IAD is much higher than in other varieties and has dropped below 1.80 at the start of harvest in the last two years.
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.
Natural Resources Disaster Relief Assistance Program (NRDRAP) Applications Due November 6
The Maine Department of Agriculture, Conservation and Forestry (DACF) is currently accepting applications for the Natural Resources Disaster Relief Assistance Program (NRDRAP). Maine farmers, forestry businesses, aquaculture producers, and other eligible producers who experienced weather-related losses in 2023 or 2024 may be able to receive financial assistance. Eligible losses may include crop loss, aquaculture loss, standing timber loss, harvested timber loss, on-farm and forestry infrastructure loss, and bare-ground practices necessary to mitigate land loss.
Application period: August 14, 2026, through November 6, 2026.
There are just over six weeks left to apply. Applicants are encouraged to begin the application process as soon as possible and reach out for help if they have questions. Applications are accepted through the online portal. Paper applications are available upon request.
For updates, eligibility information, and application details, visit MDACF’s NRDRAP webpage, by email at NRDRA.DACF@maine.gov, or call (207) 530-3144.
You can also go to the MDACF NRDRAP application portal.
DACF will continue to provide technical assistance throughout the application period. MDACF’s virtual office hours will be held from 11:00 a.m. to 1:00 p.m. on the following dates:
- September 25
- October 2
- October 9
- October 30
Renae Moran
University of Maine Cooperative Extension: Tree Fruits
PO Box 179
Monmouth, ME 04259
(207) 933-2100
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